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Microstructure and tribological behavior of amorphous and crystalline composite coatings using laser melting
Applied Surface Science 258 (2012) 6902–6908
Contents lists available at SciVerse ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Microstructure and tribological behavior of amorphous and crystalline composite coatings using laser melting Peilei Zhang ∗ , Hua Yan, Peiquan Xu, Zhishui Yu, Chonggui Li School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
a r t i c l e
i n f o
Article history: Received 28 November 2011 Received in revised form 19 March 2012 Accepted 22 March 2012 Available online 29 March 2012 Keywords: Coating Laser melting Amorphous
a b s t r a c t Four composite coatings were fabricated by laser melting. Amorphous phase appeared in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings but not in the Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The growth of crystalline grain in the coatings was suppressed greatly due to the large cooling rates caused by fast laser scanning. But the crystallization in the coatings cannot be avoided completely and an amorphous and crystalline composite coating was formed in melted zone. Amorphous phase can increase the hardness of coatings greatly and the highest hardness is related to the amount of amorphous phase in the coatings. The amorphous and crystalline composite coatings exhibit excellent performance of abrasion. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Bulk metallic glasses (BMGs) possess high strength, hardness, and elastic deformation limit [1,2]. So the amorphous materials have already attracted significant interest in the field of new materials design [3,4]. Amorphous metallic materials can be obtained by rapid quenching in order to prevent traditional solidification phenomena from occurring [5–7]. Materials with a disordered structure beyond some interatomic distances could be obtained with this method. However, these alloys find limited application as bulk structural material due to their extremely poor tensile ductility and toughness and restricted size/thickness to which they can be directly cast or fabricated. On the other hand, amorphous metallic materials can be a good candidate for wear resistant coating on metallic components [8]. In the past, lots of attempts were made to obtain amorphous coatings on crystalline substrate [9–11]. However, continued studies on amorphous coating for structural application are warranted as significant success in retaining amorphous coating and obtaining high wear resistance has not yet been achieved. Laser as a source of heat has been successfully employed to modify the microstructure and/or composition of the near surface region of a component to improve wear, corrosion and oxidation resistance of commercial metals [12–15]. However, only a few studies have utilized laser surface processing to develop amorphous
∗ Corresponding author at: Room 1615, School of Materials Engineering, 333 Long Teng Rd., Songjiang Campus of Shanghai University of Engineering Science, Shanghai 201620, China. Tel.: +86 21 67761412; fax: +86 21 67791377. E-mail address: [email protected] (P. Zhang). 0169-4332/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apsusc.2012.03.130
surface coating. Snezhnoi et al. [16] were the first to report the presence of an amorphous phase on the laser remelted chilled (ledeburitic) cast iron surface showing an average hardness of 1200 HV. Lin and Spaepen [17] used picosecond pulsed laser to irradiate Fe–B alloys and the alloys were melted and quenched into glasses. B content in these glasses is about 5 at.%, which is significantly less than the minimum 12 at.% B content required for glass formation by other liquid quenching techniques. Lin and Spaepen [17] melted Fe–B alloys to obtain a glassy layer using picosecond pulsed laser irradiation. Manna et al. [18] had made an attempt to explore deposition of Fe-based amorphous layer on plain carbon steel by LSC to improve resistance of the substrate to wear. The results showed that wear resistance of the substrate was remarkably improved. Matthews et al. fabricated amorphous coatings on titanium-based substrates successfully [19]. Chen et al. has melted the Zr-, Cu-, Fe- and Al-based alloys by laser and the amorphous or amorphous-crystalline composite structures were synthesized which were related to the different glass-forming ability of the alloys [20]. Recently, Zhang et al. has fabricated an amorphous and crystalline composite coating by laser cladding and remelting and the results show that the amount of Si plays an important role in improving the glass forming ability (GFA) of coating [21]. For the great cooling rates associated with laser surface processing, it is logical to anticipate that a crystalline substrate with high GFA is likely to produce an amorphous coating by fast laser melting. Accordingly, the present study is aimed at developing some wear resistant coatings by laser melting several cast ingots and the compositions of these alloys are in accordance with the classical Febased amorphous alloy. The coating parameters are correlated with surface microstructure and mechanical properties to determine the optimum laser surface processing conditions.
P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908
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Fig. 1. The SEM image of four master alloys.
2. Experimental procedure Four cast ingots with amorphous compositions of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 , Fe30 Co30 Ni15 B17 Si8 , Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 and Fe39 Ni36 Mo2 B18 Si5 (atom fraction, %) were prepared by arc melting a mixture of pure Fe (99.9 wt%), Ni (99.98 wt%), Mo (99.98 wt%), Co (99.98 wt%), Si (99.98 wt%), Nb (99.98 wt%) and Ferroboron (20.9 wt% B) in a water-cooled copper crucible in a Tigettered, purified argon atmosphere. The ingots were turned over and remelted at least 4 times to insure the compositional homogeneity. Rectangular plates of 2 mm in thickness, 10 mm in width and 10 mm in length for laser treatment were machined from the ingots. The plates were polished with 1500-grit SiC papers followed by cleaning and degreasing with distilled water and acetone. A 15 kW continuous CO2 laser (TRUMPF TLF15000) was used to melt the alloys. The parameters of laser melting are shown in the Table 1. The argon gas was used to protect samples from oxidation during laser processing. Rigaku X-ray diffractometry (XRD-D/max-RB, 15 kW) was used to classify the coatings with Cu K␣ irradiation ( = 0.154060 nm) while the scanning speed was 4◦ per minute and the step size was 0.02◦ . After being etched with aqua regia, the coatings were characterized by a JEOL scanning electron microscopy (SEM, JSM 6460) equipped with a unit for energy disperse spectroscopy (EDS) and with the help of a transmission
3. Results and discussion 3.1. Microstructure of cast ingots Fig. 1 shows the microstructure of four cast ingots. It is obvious that there are all crystal structures in four ingots. Lots of particle phases in the alloys can be found and the EDS tests were taken. Table 2 shows the results of EDS tests and every data is the average value of five test points in particle phases. There are elements such as Fe, Ni and Co in particle phases. It should be noted that the amount of Si in particle phases for Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 is much less than that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 . According to the Ref. [21], the amount of Si plays an important role in improving the GFA of amorphous composite coating. The
Table 2 The EDS results of particle phases in four master alloys.
Table 1 The parameters of laser melting.
Laser melting
electron microscope (TEM, PHILIPS CM200) at 200 kV. A Vickers hardness tester (HVS-10) was used to measure the microhardness of the coatings and the load is 0.2 kg. A friction wear testing machine with a pin-on-disk (MMW-1A) was used to measure the wear properties of the coatings with a load of 50 N under room temperature. A sliding disk made of GCr15 steel with a hardness of 700 HV was used.
Laser power (kW)
Scanning speed (mm/min)
Gas feed rate of argon (L/min)
Diameter of laser beam (mm)
14
8000
20–30
4
A (Fig. 1(a)) B (Fig. 1(b)) C (Fig. 1(c)) D (Fig. 1(d))
Si (At.%)
Fe (At.%)
Ni (At.%)
Co (At.%)
Mo (At.%)
0.74 5.50 0.26 2.37
84.32 49.53 65.68 47.69
14.94 13.35 16.17 45.67
– 37.62 17.89 –
– – – 4.27
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P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908 Table 3 The mixing enthalpies between columbium and other elements. Mixing enthalpies (kJ/mol)
Fig. 2. The SEM image of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 alloy after laser melting.
different amount of Si in four alloys may affect the formation of amorphous phase in laser processing. 3.2. Microstructure of coatings Fig. 2 shows the macroscopic image of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating and the depth is about 200–300 m. The coating surface is a bit cave and it indicated that there was only a little metal loss in laser processing. The reason may be attributed to the large cooling rate brought by fast laser scanning. This is of great advantage to obtain widespread coating because it will not be necessary to machining the coating for smooth surface after laser processing. Fig. 3 shows the XRD patterns of four coatings. The intensity of the diffraction peaks in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings is much lower than that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The diffraction peaks of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings are broadened and it reveals an apparent amorphous structural characteristic within the detect limitation of the XRD. In other words, the crystalline phases are depressed and the amorphous phase is the principal phase in these coatings. Several peaks corresponding to crystalline phases imposed on the diffused diffraction maxima, which mean that crystalline phases also exist in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings. The crystalline phases are identified as Fe2 B, Fe23 B6 , ␥-(Fe,Ni) and so on which are shown in Fig. 3(a) and (c). However, there are steep diffraction peaks in the XRD patterns of coatings for Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 and it indicates that no amorphous phase appeared obviously in these coatings. In other words, the GFA of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 alloys are rather higher than that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 alloys in laser processing. Columbium was added into Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 alloys but not in the other two alloys. According to empirical rules, there are mainly two positive effects of columbium on improving the GFA of alloys. First of all, the radius of columbium atom is the largest in four alloys. Additions of large atoms in a system increase the atomic size mismatches among all constituents. Based on one of the so-called Hume–Rothery rules [22], the solubility of these added large atoms in the competing crystalline phases containing one or a plurality of major constituents is likely restricted. In molten liquids, small amounts of these large atoms can be dissolved homogeneously. Additions of large atoms in off-eutectic alloys tend to effectively suppress the formation of the competing crystalline phases and adjust the
Nb–Fe
Nb–Co
Nb–Ni
Nb–B
Nb–Si
−16
−25
−30
−54
−56
composition close to the eutectic, thereby lowering the melting point (i.e., the liquid phase is stabilized). Large elements generally have a high tendency of compound formation with major constituents in a base alloy [23,24], which increases its short-range compositional ordering and favors the formation of clusters in the undercooled liquids. It was experimentally confirmed that the local chemical configuration of the clusters in undercooled liquids was extremely different from that of the long-range crystalline ordering [25]. A stronger chemical short-range ordering due to the additions of the large atoms tends to enhance the liquid phase stability and, in turn, retards the crystallization process. During the crystallization process upon cooling, these atoms have to be redistributed (i.e., long range inter-diffusions are required) due to their limited solubility in the competing crystalline phases. The added large atoms have to be redistributed during the crystallization process upon cooling. The additions of these atoms make it difficult for the concentrations of all elements to simultaneously satisfy the composition requirements of the crystalline nucleus. This is because long-range rearrangement of more kinds of atoms is involved. Rejecting these large atoms from the crystalline nucleus changes the composition and interfacial energy at the solid/liquid interface. In addition, necessary long-range inter-diffusions slow down the subsequent crystal growth rate of the nucleus. All of these contributions suppress the formation and growth of the competing crystalline phases. In turn, the glass formation is promoted [25]. Secondly, according to the theory of cohesion in metals [23], columbium atoms have a large negative heat of mixing with other small or intermediate atoms (i.e., the atomic bonding between these elements are typically strong). The mixing enthalpies between columbium and other elements in the alloys are shown in Table 3. It is obvious that the mixing enthalpies between columbium and other elements are negative. The negative mixing enthalpy of Si–Nb is as large as 56 kJ/mol. It has high tendency to form compounds instead of solid solutions. As a result, addition of a little columbium is a very effective way of improving the GFA of coatings in laser processing. It agrees well with the XRD results discussed above and the coatings containing Nb demonstrate good GFA in laser processing. The content of Si in particle phases varied widely base on the EDS results shown in Table 2. Less Si in the particle phases is beneficial to form amorphous phases in laser melting. This is because that the less Si in the particle phases, the more Si may be retained in the matrix of alloys. Si is very easy to react with oxygen and the loss of other elements in laser processing will decrease with increasing the content of Si. The proper content of Si is critical to form amorphous phase in the coatings [21]. Therefore, amorphous phase appeared in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings but not in that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. Fig. 4 shows the SEM image of four coatings. Many grains appear in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings. Some dendrites appear in the Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The EDS results of the particle phases in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings are shown in Table 4. According to the EDS and XRD results, these particle phases may be metallic compounds such as Fe2 B, ␥-(Fe,Ni) and so on. It can be seen from Fig. 3(a) that the size of particle phases is about 1 m. It indicates that the crystal growth was
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Fig. 3. The XRD patterns of the melted zone.
suppressed greatly due to the large cooling rates in solidification caused by laser. In order to make further investigations on the phase composition in the Fe31 Ni31 Si18 B18 Nb2 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings, TEM analysis was carried out. Figs. 5 and 6 present the TEM images and the selected area electron diffraction patterns of the Fe31 Ni31 Si18 B18 Nb2 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings respectively. The bright-field image as shown in Fig. 5(a) reveals a typical amorphous matrix and some black/gray crystalline phases embedded in the matrix. The white phase (region A) is the amorphous phase and its selected area electron diffraction pattern which consists of halo rings typical of an amorphous phase is shown in Fig. 5(b). The results indicate that a substantial amount of an amorphous phase exists in the coating. In addition, there are Fe2 B and ␥-(Fe,Ni) in the black phase (region B) and their selected area electron diffraction patterns are shown in Fig. 5(c). In conclusion, there are amorphous phase, Fe2 B and ␥-(Fe,Ni) in Fe31 Ni31 Si18 B18 Nb2 coating. Similarly, it can be seen from Fig. 6 that there are amorphous phase and Fe2 B and NiSi in Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coating. It should be noted that the amount of amorphous phase in the Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coating may be less than that in the Fe31 Ni31 Si18 B18 Nb2 Table 4 The EDS results of the particle phases in melted zone for Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 alloys.
A (Fig. 4(a)) B (Fig. 4(c))
Si (At.%)
Fe (At.%)
Ni (At.%)
Nb (At.%)
Co (At.%)
13 10
49 52
31 14
7 15
– 9
coating according to the area of white phase in the TEM images which are shown in Fig. 5(a) and Fig. 6(a) respectively.Admittedly, there are still many crystal grains in the coatings. In other words, the crystallization cannot be avoided completely in laser melting. This problem is intrinsically complicated. The formation of amorphous phase is related to the GFA of the alloys, nucleation rate, solidification rate, suppression of crystal growth, laser irradiate time and so on. The formation mechanism of amorphous phase in BMGs and coating is differernt. In BMGs, restraining heterogeneous nucleation is the main method to obtain amorphous phase. In laser amorphization, suppressing growth of the nuclei is a primary approach to gain an amorphous coating. The reason is that the nucleation is difficult to be avoided in laser processing. The crystal nucleus can come from the high temperature oxides, un-melted crystal grains, high melting point compounds and so on. Certainly, if amorphous coating is fabricated in a vacuum tank by laser, the amount of crystalline phase will sharply reduce. But the cost of making amorphous coating will rise rapidly. Therefore, how to obtain amorphous phase as much as possible by laser processing and meanwhile keep costs down is a huge challenge.
3.3. Microhardness of the coatings Fig. 7 shows the microhardness of the four coatings. It can be seen that the hardness increases greatly after laser melting. It can be attributed to two main reasons. Firstly, the amorphous phases appeared in the coatings and the Fe-based amorphous phase has a high hardness which can be more than 1000 HV. The hardness of
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P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908
Fig. 4. SEM analysis of four alloys after laser melting.
Fig. 5. The TEM image and selected area electron diffraction pattern of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 . (a) The TEM image of remelted zone. (b) Selected electron diffraction pattern of region A. (c) Selected electron diffraction pattern of region B.
P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908
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Fig. 6. The TEM image and selected area electron diffraction pattern of Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 . (a) The TEM image of remelted zone. (b) Selected electron diffraction pattern of region A. (c) Selected electron diffraction pattern of region B.
amorphous phase is far exceeded than that of the crystal alloy with the same composition. Secondly, the hardness increased greatly by grain refinement in laser processing. In a word, the Fe-based amorphous and crystalline composite coatings have the extremely high hardness and it has more advantage in abrasion resistance. The hardness of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating is the highest in four alloys. Due to the same cooling rates, it may be deduced that the content of amorphous phase in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating is the most and it can be verified in the TEM analysis mentioned above.
Fig. 7. Microhardness of melted zone for four alloys.
3.4. Tribological measurement of coatings The tribological performance of the composite coatings was assessed by dry sliding wear tests. Fig. 8 shows that, with the increase of wear time, the wear loss increases rapidly. Wear loss of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating is the least and that of Fe30 Co30 Ni15 B17 Si8 coating is the largest at the end of wear test. The wear loss volume removed from Fe30 Co30 Ni15 B17 Si8 coating is about 2 times larger than that of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating at the wear time of 60 min. These results accord with that of hardness
Fig. 8. Wear loss against wear time.
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and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings but not in that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The elements Nb and Si show obvious positive effects on improving the GFA of coatings. The amorphous phase can increase the hardness of coatings greatly and the highest hardness is related to content of amorphous phase and grain refinement in the coatings. The amorphous and crystalline composite coatings exhibit excellent performance of abrasion. Acknowledgments This research was supported by Foundation of Shanghai University of Engineering Science, China (grant no. A-0501-11-009 and A-0501-11-008), Aid Project of Youth Teacher Training in Colleges and Universities of Shanghai, China (grant no. shgcjs002,003,025), the National Natural Science Foundation of China (no. 50875160 and 51105240) and the Shanghai Leading Academic Discipline Project, China (grant no. J51402). Fig. 9. Friction coefficient against wear time.
References tests and it indicates that the harder coating brought about the less wear loss. Fig. 9 shows the friction coefficient curves of four coatings. According to molecular-kinetic and mechanical model theories of the frictional behavior of elastomeric materials [26], the magnitude of the friction coefficient is inversely proportional to the hardness of the alloy surfaces. The friction experiment indicates that the coatings containing amorphous phase demonstrate less friction coefficient. The friction coefficient initially increases quickly with increasing sliding time, which corresponds to a high-wear runningin period and then it tends to stabilize after sliding for about 10 min. Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings have a smaller friction coefficient than that of the other two coatings. The better wear resistance of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings may be attributed to the amorphous phase in the coatings. It can be concluded that the GFA of alloy also has an important influence on the friction and wear behavior of coatings irradiated by laser. In other words, the amorphous and crystalline composite coating has excellent wear resistance compared with crystalline coating. 4. Conclusion Coatings with amorphous phase, small grains and dendritic structures were formed after laser melting four cast ingots. Amorphous phase appeared in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26]
J. Fornell, S. González, E. Rossinyol, Acta Mater. 58 (2010) 6256. H.Y. Jung, S. Yi, Intermetallics 18 (2010) 1936. S.F. Guo, N. Li, C. Zhang, L. Liu, J. Alloys Compd. 504 (2010) S78. T. Terajima, F. Takeuchi, K. Nakata, J. Alloys Compd. 504 (2010) S288. J. Torrens-Serra, P. Bruna, J. Rodríguez-Viejo, S. Roth, M.T. Clavaguera-Mora, Intermetallics 18 (2010) 773. E. Salahinejad, R. Amini, M. Marasi, Mater. Chem. Phys. 118 (2009) 71. J.S.-C. Jang, S.-R. Jian, T.-H. Li, J. Alloys Compd. 485 (2009) 290. A. Basu, A.N. Samant, S.P. Harimkar, J. Dutta Majumdar, I. Manna, N.B. Dahotre, Surf. Coat. Technol. 202 (2008) 2623. S. Yoon, J. Kim, B.D. Kim, Surf. Coat. Technol. 205 (2010) 1962. A. Kobayashi, T. Kuroda, H. Kimura, Mater. Sci. Eng. B 173 (2010) 122. Z. Peilei, L. Zhuguo, Y. Chengwu, Adv. Mater. Res. 97–101 (2010) 1420. J. Dutta-Majumdar, I. Manna, Mater. Sci. Eng. A 268 (1999) 227. N. Amanat, C. Chaminade, J. Grace, Mater. Des. 31 (2010) 4823. J. Dutta-Majumdar, A. Weisheit, B.L. Mordike, I. Manna, Mater. Sci. Eng. A 266 (1999) 123. ˜ V.K. Balla, A. Bandyopadhyay, Surf. Coat. Technol. 204 (2010) F.A. Espana, 2510. R.L. Snezhnoi, A.A. Zhukov, A.N. Kokora, Metal Sci. Heat Treat. 22 (1980) 900. C.J. Lin, F. Spaepen, Appl. Phys. Lett. 41 (1982) 721. I. Manna, J. Dutta-Majumdar, B.R. Chandra, S. Nayak, N.B. Dahotre, Surf. Coat. Technol. 201 (2006) 434. D.T.A. Matthews, V. Ocelik, J.T.M. de Hosson, Mater. Sci. Eng. A 471 (2007) 155. B. Chen, Y. Li, Y. Cai, R. Li, S. Pang, T. Zhang, J. Alloys Compd. 511 (2012) 215. P. Zhang, H. Yan, C. Yao, Z. Li, Z. Yu, P. Xu, Surf. Coat. Technol. 206 (2011) 1229. M.H. Richman, An Introduction to Physical Metallurgy, Massachusetts, Blaisdell, 1967. A. Inoue, Mater. Trans. 46 (2005) 2817. F.R. De Boer, R. Boom, A.R. Miedema, et al., Cohesion in Metal Alloy, Physics Publishing House, Amsterdam, Netherlands, pNorth-Holland, 1989. Z.P. Lu, C.T. Liu, J. Mater. Res. 39 (2004) 3965. D.F. Moore, Pergamon, Oxford, 1972.
Contents lists available at SciVerse ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Microstructure and tribological behavior of amorphous and crystalline composite coatings using laser melting Peilei Zhang ∗ , Hua Yan, Peiquan Xu, Zhishui Yu, Chonggui Li School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
a r t i c l e
i n f o
Article history: Received 28 November 2011 Received in revised form 19 March 2012 Accepted 22 March 2012 Available online 29 March 2012 Keywords: Coating Laser melting Amorphous
a b s t r a c t Four composite coatings were fabricated by laser melting. Amorphous phase appeared in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings but not in the Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The growth of crystalline grain in the coatings was suppressed greatly due to the large cooling rates caused by fast laser scanning. But the crystallization in the coatings cannot be avoided completely and an amorphous and crystalline composite coating was formed in melted zone. Amorphous phase can increase the hardness of coatings greatly and the highest hardness is related to the amount of amorphous phase in the coatings. The amorphous and crystalline composite coatings exhibit excellent performance of abrasion. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Bulk metallic glasses (BMGs) possess high strength, hardness, and elastic deformation limit [1,2]. So the amorphous materials have already attracted significant interest in the field of new materials design [3,4]. Amorphous metallic materials can be obtained by rapid quenching in order to prevent traditional solidification phenomena from occurring [5–7]. Materials with a disordered structure beyond some interatomic distances could be obtained with this method. However, these alloys find limited application as bulk structural material due to their extremely poor tensile ductility and toughness and restricted size/thickness to which they can be directly cast or fabricated. On the other hand, amorphous metallic materials can be a good candidate for wear resistant coating on metallic components [8]. In the past, lots of attempts were made to obtain amorphous coatings on crystalline substrate [9–11]. However, continued studies on amorphous coating for structural application are warranted as significant success in retaining amorphous coating and obtaining high wear resistance has not yet been achieved. Laser as a source of heat has been successfully employed to modify the microstructure and/or composition of the near surface region of a component to improve wear, corrosion and oxidation resistance of commercial metals [12–15]. However, only a few studies have utilized laser surface processing to develop amorphous
∗ Corresponding author at: Room 1615, School of Materials Engineering, 333 Long Teng Rd., Songjiang Campus of Shanghai University of Engineering Science, Shanghai 201620, China. Tel.: +86 21 67761412; fax: +86 21 67791377. E-mail address: [email protected] (P. Zhang). 0169-4332/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apsusc.2012.03.130
surface coating. Snezhnoi et al. [16] were the first to report the presence of an amorphous phase on the laser remelted chilled (ledeburitic) cast iron surface showing an average hardness of 1200 HV. Lin and Spaepen [17] used picosecond pulsed laser to irradiate Fe–B alloys and the alloys were melted and quenched into glasses. B content in these glasses is about 5 at.%, which is significantly less than the minimum 12 at.% B content required for glass formation by other liquid quenching techniques. Lin and Spaepen [17] melted Fe–B alloys to obtain a glassy layer using picosecond pulsed laser irradiation. Manna et al. [18] had made an attempt to explore deposition of Fe-based amorphous layer on plain carbon steel by LSC to improve resistance of the substrate to wear. The results showed that wear resistance of the substrate was remarkably improved. Matthews et al. fabricated amorphous coatings on titanium-based substrates successfully [19]. Chen et al. has melted the Zr-, Cu-, Fe- and Al-based alloys by laser and the amorphous or amorphous-crystalline composite structures were synthesized which were related to the different glass-forming ability of the alloys [20]. Recently, Zhang et al. has fabricated an amorphous and crystalline composite coating by laser cladding and remelting and the results show that the amount of Si plays an important role in improving the glass forming ability (GFA) of coating [21]. For the great cooling rates associated with laser surface processing, it is logical to anticipate that a crystalline substrate with high GFA is likely to produce an amorphous coating by fast laser melting. Accordingly, the present study is aimed at developing some wear resistant coatings by laser melting several cast ingots and the compositions of these alloys are in accordance with the classical Febased amorphous alloy. The coating parameters are correlated with surface microstructure and mechanical properties to determine the optimum laser surface processing conditions.
P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908
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Fig. 1. The SEM image of four master alloys.
2. Experimental procedure Four cast ingots with amorphous compositions of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 , Fe30 Co30 Ni15 B17 Si8 , Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 and Fe39 Ni36 Mo2 B18 Si5 (atom fraction, %) were prepared by arc melting a mixture of pure Fe (99.9 wt%), Ni (99.98 wt%), Mo (99.98 wt%), Co (99.98 wt%), Si (99.98 wt%), Nb (99.98 wt%) and Ferroboron (20.9 wt% B) in a water-cooled copper crucible in a Tigettered, purified argon atmosphere. The ingots were turned over and remelted at least 4 times to insure the compositional homogeneity. Rectangular plates of 2 mm in thickness, 10 mm in width and 10 mm in length for laser treatment were machined from the ingots. The plates were polished with 1500-grit SiC papers followed by cleaning and degreasing with distilled water and acetone. A 15 kW continuous CO2 laser (TRUMPF TLF15000) was used to melt the alloys. The parameters of laser melting are shown in the Table 1. The argon gas was used to protect samples from oxidation during laser processing. Rigaku X-ray diffractometry (XRD-D/max-RB, 15 kW) was used to classify the coatings with Cu K␣ irradiation ( = 0.154060 nm) while the scanning speed was 4◦ per minute and the step size was 0.02◦ . After being etched with aqua regia, the coatings were characterized by a JEOL scanning electron microscopy (SEM, JSM 6460) equipped with a unit for energy disperse spectroscopy (EDS) and with the help of a transmission
3. Results and discussion 3.1. Microstructure of cast ingots Fig. 1 shows the microstructure of four cast ingots. It is obvious that there are all crystal structures in four ingots. Lots of particle phases in the alloys can be found and the EDS tests were taken. Table 2 shows the results of EDS tests and every data is the average value of five test points in particle phases. There are elements such as Fe, Ni and Co in particle phases. It should be noted that the amount of Si in particle phases for Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 is much less than that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 . According to the Ref. [21], the amount of Si plays an important role in improving the GFA of amorphous composite coating. The
Table 2 The EDS results of particle phases in four master alloys.
Table 1 The parameters of laser melting.
Laser melting
electron microscope (TEM, PHILIPS CM200) at 200 kV. A Vickers hardness tester (HVS-10) was used to measure the microhardness of the coatings and the load is 0.2 kg. A friction wear testing machine with a pin-on-disk (MMW-1A) was used to measure the wear properties of the coatings with a load of 50 N under room temperature. A sliding disk made of GCr15 steel with a hardness of 700 HV was used.
Laser power (kW)
Scanning speed (mm/min)
Gas feed rate of argon (L/min)
Diameter of laser beam (mm)
14
8000
20–30
4
A (Fig. 1(a)) B (Fig. 1(b)) C (Fig. 1(c)) D (Fig. 1(d))
Si (At.%)
Fe (At.%)
Ni (At.%)
Co (At.%)
Mo (At.%)
0.74 5.50 0.26 2.37
84.32 49.53 65.68 47.69
14.94 13.35 16.17 45.67
– 37.62 17.89 –
– – – 4.27
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P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908 Table 3 The mixing enthalpies between columbium and other elements. Mixing enthalpies (kJ/mol)
Fig. 2. The SEM image of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 alloy after laser melting.
different amount of Si in four alloys may affect the formation of amorphous phase in laser processing. 3.2. Microstructure of coatings Fig. 2 shows the macroscopic image of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating and the depth is about 200–300 m. The coating surface is a bit cave and it indicated that there was only a little metal loss in laser processing. The reason may be attributed to the large cooling rate brought by fast laser scanning. This is of great advantage to obtain widespread coating because it will not be necessary to machining the coating for smooth surface after laser processing. Fig. 3 shows the XRD patterns of four coatings. The intensity of the diffraction peaks in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings is much lower than that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The diffraction peaks of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings are broadened and it reveals an apparent amorphous structural characteristic within the detect limitation of the XRD. In other words, the crystalline phases are depressed and the amorphous phase is the principal phase in these coatings. Several peaks corresponding to crystalline phases imposed on the diffused diffraction maxima, which mean that crystalline phases also exist in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings. The crystalline phases are identified as Fe2 B, Fe23 B6 , ␥-(Fe,Ni) and so on which are shown in Fig. 3(a) and (c). However, there are steep diffraction peaks in the XRD patterns of coatings for Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 and it indicates that no amorphous phase appeared obviously in these coatings. In other words, the GFA of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 alloys are rather higher than that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 alloys in laser processing. Columbium was added into Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 alloys but not in the other two alloys. According to empirical rules, there are mainly two positive effects of columbium on improving the GFA of alloys. First of all, the radius of columbium atom is the largest in four alloys. Additions of large atoms in a system increase the atomic size mismatches among all constituents. Based on one of the so-called Hume–Rothery rules [22], the solubility of these added large atoms in the competing crystalline phases containing one or a plurality of major constituents is likely restricted. In molten liquids, small amounts of these large atoms can be dissolved homogeneously. Additions of large atoms in off-eutectic alloys tend to effectively suppress the formation of the competing crystalline phases and adjust the
Nb–Fe
Nb–Co
Nb–Ni
Nb–B
Nb–Si
−16
−25
−30
−54
−56
composition close to the eutectic, thereby lowering the melting point (i.e., the liquid phase is stabilized). Large elements generally have a high tendency of compound formation with major constituents in a base alloy [23,24], which increases its short-range compositional ordering and favors the formation of clusters in the undercooled liquids. It was experimentally confirmed that the local chemical configuration of the clusters in undercooled liquids was extremely different from that of the long-range crystalline ordering [25]. A stronger chemical short-range ordering due to the additions of the large atoms tends to enhance the liquid phase stability and, in turn, retards the crystallization process. During the crystallization process upon cooling, these atoms have to be redistributed (i.e., long range inter-diffusions are required) due to their limited solubility in the competing crystalline phases. The added large atoms have to be redistributed during the crystallization process upon cooling. The additions of these atoms make it difficult for the concentrations of all elements to simultaneously satisfy the composition requirements of the crystalline nucleus. This is because long-range rearrangement of more kinds of atoms is involved. Rejecting these large atoms from the crystalline nucleus changes the composition and interfacial energy at the solid/liquid interface. In addition, necessary long-range inter-diffusions slow down the subsequent crystal growth rate of the nucleus. All of these contributions suppress the formation and growth of the competing crystalline phases. In turn, the glass formation is promoted [25]. Secondly, according to the theory of cohesion in metals [23], columbium atoms have a large negative heat of mixing with other small or intermediate atoms (i.e., the atomic bonding between these elements are typically strong). The mixing enthalpies between columbium and other elements in the alloys are shown in Table 3. It is obvious that the mixing enthalpies between columbium and other elements are negative. The negative mixing enthalpy of Si–Nb is as large as 56 kJ/mol. It has high tendency to form compounds instead of solid solutions. As a result, addition of a little columbium is a very effective way of improving the GFA of coatings in laser processing. It agrees well with the XRD results discussed above and the coatings containing Nb demonstrate good GFA in laser processing. The content of Si in particle phases varied widely base on the EDS results shown in Table 2. Less Si in the particle phases is beneficial to form amorphous phases in laser melting. This is because that the less Si in the particle phases, the more Si may be retained in the matrix of alloys. Si is very easy to react with oxygen and the loss of other elements in laser processing will decrease with increasing the content of Si. The proper content of Si is critical to form amorphous phase in the coatings [21]. Therefore, amorphous phase appeared in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings but not in that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. Fig. 4 shows the SEM image of four coatings. Many grains appear in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings. Some dendrites appear in the Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The EDS results of the particle phases in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings are shown in Table 4. According to the EDS and XRD results, these particle phases may be metallic compounds such as Fe2 B, ␥-(Fe,Ni) and so on. It can be seen from Fig. 3(a) that the size of particle phases is about 1 m. It indicates that the crystal growth was
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Fig. 3. The XRD patterns of the melted zone.
suppressed greatly due to the large cooling rates in solidification caused by laser. In order to make further investigations on the phase composition in the Fe31 Ni31 Si18 B18 Nb2 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings, TEM analysis was carried out. Figs. 5 and 6 present the TEM images and the selected area electron diffraction patterns of the Fe31 Ni31 Si18 B18 Nb2 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings respectively. The bright-field image as shown in Fig. 5(a) reveals a typical amorphous matrix and some black/gray crystalline phases embedded in the matrix. The white phase (region A) is the amorphous phase and its selected area electron diffraction pattern which consists of halo rings typical of an amorphous phase is shown in Fig. 5(b). The results indicate that a substantial amount of an amorphous phase exists in the coating. In addition, there are Fe2 B and ␥-(Fe,Ni) in the black phase (region B) and their selected area electron diffraction patterns are shown in Fig. 5(c). In conclusion, there are amorphous phase, Fe2 B and ␥-(Fe,Ni) in Fe31 Ni31 Si18 B18 Nb2 coating. Similarly, it can be seen from Fig. 6 that there are amorphous phase and Fe2 B and NiSi in Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coating. It should be noted that the amount of amorphous phase in the Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coating may be less than that in the Fe31 Ni31 Si18 B18 Nb2 Table 4 The EDS results of the particle phases in melted zone for Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 alloys.
A (Fig. 4(a)) B (Fig. 4(c))
Si (At.%)
Fe (At.%)
Ni (At.%)
Nb (At.%)
Co (At.%)
13 10
49 52
31 14
7 15
– 9
coating according to the area of white phase in the TEM images which are shown in Fig. 5(a) and Fig. 6(a) respectively.Admittedly, there are still many crystal grains in the coatings. In other words, the crystallization cannot be avoided completely in laser melting. This problem is intrinsically complicated. The formation of amorphous phase is related to the GFA of the alloys, nucleation rate, solidification rate, suppression of crystal growth, laser irradiate time and so on. The formation mechanism of amorphous phase in BMGs and coating is differernt. In BMGs, restraining heterogeneous nucleation is the main method to obtain amorphous phase. In laser amorphization, suppressing growth of the nuclei is a primary approach to gain an amorphous coating. The reason is that the nucleation is difficult to be avoided in laser processing. The crystal nucleus can come from the high temperature oxides, un-melted crystal grains, high melting point compounds and so on. Certainly, if amorphous coating is fabricated in a vacuum tank by laser, the amount of crystalline phase will sharply reduce. But the cost of making amorphous coating will rise rapidly. Therefore, how to obtain amorphous phase as much as possible by laser processing and meanwhile keep costs down is a huge challenge.
3.3. Microhardness of the coatings Fig. 7 shows the microhardness of the four coatings. It can be seen that the hardness increases greatly after laser melting. It can be attributed to two main reasons. Firstly, the amorphous phases appeared in the coatings and the Fe-based amorphous phase has a high hardness which can be more than 1000 HV. The hardness of
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Fig. 4. SEM analysis of four alloys after laser melting.
Fig. 5. The TEM image and selected area electron diffraction pattern of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 . (a) The TEM image of remelted zone. (b) Selected electron diffraction pattern of region A. (c) Selected electron diffraction pattern of region B.
P. Zhang et al. / Applied Surface Science 258 (2012) 6902–6908
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Fig. 6. The TEM image and selected area electron diffraction pattern of Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 . (a) The TEM image of remelted zone. (b) Selected electron diffraction pattern of region A. (c) Selected electron diffraction pattern of region B.
amorphous phase is far exceeded than that of the crystal alloy with the same composition. Secondly, the hardness increased greatly by grain refinement in laser processing. In a word, the Fe-based amorphous and crystalline composite coatings have the extremely high hardness and it has more advantage in abrasion resistance. The hardness of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating is the highest in four alloys. Due to the same cooling rates, it may be deduced that the content of amorphous phase in Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating is the most and it can be verified in the TEM analysis mentioned above.
Fig. 7. Microhardness of melted zone for four alloys.
3.4. Tribological measurement of coatings The tribological performance of the composite coatings was assessed by dry sliding wear tests. Fig. 8 shows that, with the increase of wear time, the wear loss increases rapidly. Wear loss of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating is the least and that of Fe30 Co30 Ni15 B17 Si8 coating is the largest at the end of wear test. The wear loss volume removed from Fe30 Co30 Ni15 B17 Si8 coating is about 2 times larger than that of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 coating at the wear time of 60 min. These results accord with that of hardness
Fig. 8. Wear loss against wear time.
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and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings but not in that of Fe30 Co30 Ni15 B17 Si8 and Fe39 Ni36 Mo2 B18 Si5 coatings. The elements Nb and Si show obvious positive effects on improving the GFA of coatings. The amorphous phase can increase the hardness of coatings greatly and the highest hardness is related to content of amorphous phase and grain refinement in the coatings. The amorphous and crystalline composite coatings exhibit excellent performance of abrasion. Acknowledgments This research was supported by Foundation of Shanghai University of Engineering Science, China (grant no. A-0501-11-009 and A-0501-11-008), Aid Project of Youth Teacher Training in Colleges and Universities of Shanghai, China (grant no. shgcjs002,003,025), the National Natural Science Foundation of China (no. 50875160 and 51105240) and the Shanghai Leading Academic Discipline Project, China (grant no. J51402). Fig. 9. Friction coefficient against wear time.
References tests and it indicates that the harder coating brought about the less wear loss. Fig. 9 shows the friction coefficient curves of four coatings. According to molecular-kinetic and mechanical model theories of the frictional behavior of elastomeric materials [26], the magnitude of the friction coefficient is inversely proportional to the hardness of the alloy surfaces. The friction experiment indicates that the coatings containing amorphous phase demonstrate less friction coefficient. The friction coefficient initially increases quickly with increasing sliding time, which corresponds to a high-wear runningin period and then it tends to stabilize after sliding for about 10 min. Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings have a smaller friction coefficient than that of the other two coatings. The better wear resistance of Fe43.2 Ni28.8 B19.2 Si4.8 Nb4 and Fe43.2 Co14.4 Ni14.4 B19.2 Si4.8 Nb4 coatings may be attributed to the amorphous phase in the coatings. It can be concluded that the GFA of alloy also has an important influence on the friction and wear behavior of coatings irradiated by laser. In other words, the amorphous and crystalline composite coating has excellent wear resistance compared with crystalline coating. 4. Conclusion Coatings with amorphous phase, small grains and dendritic structures were formed after laser melting four cast ingots. Amorphous phase appeared in the Fe43.2 Ni28.8 B19.2 Si4.8 Nb4
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26]
J. Fornell, S. González, E. Rossinyol, Acta Mater. 58 (2010) 6256. H.Y. Jung, S. Yi, Intermetallics 18 (2010) 1936. S.F. Guo, N. Li, C. Zhang, L. Liu, J. Alloys Compd. 504 (2010) S78. T. Terajima, F. Takeuchi, K. Nakata, J. Alloys Compd. 504 (2010) S288. J. Torrens-Serra, P. Bruna, J. Rodríguez-Viejo, S. Roth, M.T. Clavaguera-Mora, Intermetallics 18 (2010) 773. E. Salahinejad, R. Amini, M. Marasi, Mater. Chem. Phys. 118 (2009) 71. J.S.-C. Jang, S.-R. Jian, T.-H. Li, J. Alloys Compd. 485 (2009) 290. A. Basu, A.N. Samant, S.P. Harimkar, J. Dutta Majumdar, I. Manna, N.B. Dahotre, Surf. Coat. Technol. 202 (2008) 2623. S. Yoon, J. Kim, B.D. Kim, Surf. Coat. Technol. 205 (2010) 1962. A. Kobayashi, T. Kuroda, H. Kimura, Mater. Sci. Eng. B 173 (2010) 122. Z. Peilei, L. Zhuguo, Y. Chengwu, Adv. Mater. Res. 97–101 (2010) 1420. J. Dutta-Majumdar, I. Manna, Mater. Sci. Eng. A 268 (1999) 227. N. Amanat, C. Chaminade, J. Grace, Mater. Des. 31 (2010) 4823. J. Dutta-Majumdar, A. Weisheit, B.L. Mordike, I. Manna, Mater. Sci. Eng. A 266 (1999) 123. ˜ V.K. Balla, A. Bandyopadhyay, Surf. Coat. Technol. 204 (2010) F.A. Espana, 2510. R.L. Snezhnoi, A.A. Zhukov, A.N. Kokora, Metal Sci. Heat Treat. 22 (1980) 900. C.J. Lin, F. Spaepen, Appl. Phys. Lett. 41 (1982) 721. I. Manna, J. Dutta-Majumdar, B.R. Chandra, S. Nayak, N.B. Dahotre, Surf. Coat. Technol. 201 (2006) 434. D.T.A. Matthews, V. Ocelik, J.T.M. de Hosson, Mater. Sci. Eng. A 471 (2007) 155. B. Chen, Y. Li, Y. Cai, R. Li, S. Pang, T. Zhang, J. Alloys Compd. 511 (2012) 215. P. Zhang, H. Yan, C. Yao, Z. Li, Z. Yu, P. Xu, Surf. Coat. Technol. 206 (2011) 1229. M.H. Richman, An Introduction to Physical Metallurgy, Massachusetts, Blaisdell, 1967. A. Inoue, Mater. Trans. 46 (2005) 2817. F.R. De Boer, R. Boom, A.R. Miedema, et al., Cohesion in Metal Alloy, Physics Publishing House, Amsterdam, Netherlands, pNorth-Holland, 1989. Z.P. Lu, C.T. Liu, J. Mater. Res. 39 (2004) 3965. D.F. Moore, Pergamon, Oxford, 1972.