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Effect of cooling rate on the phase structure and magnetic properties of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 high entropy alloy
Journal of Magnetism and Magnetic Materials 435 (2017) 184–186
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Effect of cooling rate on the phase structure and magnetic properties of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 high entropy alloy Ran Wei a, Huan Sun a, Chen Chen a, Zhenhua Han b, Fushan Li a,⇑ a b
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710068, China
a r t i c l e
i n f o
Article history: Received 22 January 2017 Received in revised form 24 March 2017 Accepted 7 April 2017 Available online 9 April 2017 Keywords: High entropy alloy Amorphous alloys Soft magnetic properties Annealing Phase transformation
a b s t r a c t The effect of cooling rate on phase structure and magnetic properties of the Fe26.7Co28.5Ni28.5Si4.6B8.7P3 high entropy alloy (HEA) was investigated. The HEA forms into amorphous phase by melt spinning method at high cooling rate and FCC solid solution phase at low cooling rate. The soft magnetic properties of the amorphous phase (saturation magnetization Bs of 1.07T and coercivity Hc of 4 A/m) are better than that of the solid solution phase (Bs of 1.0 T and Hc of 168 A/m). In order to study the phase evolution of the present HEA, anneal experiments were conducted. It is found that crystallization products of amorphous phase are solid solution phase which constitute much of FCC and a small amount of BCC. BCC phase transforms into FCC phase, and then into BCC phase with the increase of annealing temperature. Ó 2017 Elsevier B.V. All rights reserved.
1. Introduction High entropy alloys (HEAs) are a class of alloys with multiprincipal elements at equimolar ratio or with concentrations between 5 and 35 at.% [1]. Some HEAs have been reported to exhibit simple crystal structures such as body-centred cubic (BCC) or face-centred cubic (FCC), some other HEAs can form amorphous structures [2]. HEAs are receiving much attention for their unique structures as well as excellent performances [3–7]. Recently, many researches are conducted to understand their phase evolution, and thus to design microstructural [4,8,9]. BCC phase was obtained in CoCrFeNi HEA by supercooling method to enhance its mechanical properties [8]. By tailoring the alloy composition of AlxSi0.2CrCoFeNiCu1 x HEAs, rapid cooling rate can promote the formation of FCC or BCC in these HEAs, and then different mechanical properties were obtained [4]. Al0.5TiZrPdCuNi HEA can form single amorphous phase by melt spinning method at high cooling rate and single BCC solid solution phase by copper-mold casting at low cooling rate [10]. However, the effects of cooling rate on phase structure, especially magnetic properties of HEAs, leading to formation of amorphous phase or simple solid solution phase, are still limited. In this work, Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA constituted only by ferromagnetic elements and metalloids which favors good soft ⇑ Corresponding author. E-mail address: [email protected] (F. Li). http://dx.doi.org/10.1016/j.jmmm.2017.04.017 0304-8853/Ó 2017 Elsevier B.V. All rights reserved.
magnetic properties, with amorphous phase and simple solid solution phase were prepared respectively by melt-spinning method. The effect of cooling rate on the phase structure and magnetic properties of the present HEA was discussed in detail. The phase evolution of the amorphous phase was studied.
2. Experimental procedure Alloy ingot of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 (at.%) was prepared by induction melting of industrial pure materials under argon atmosphere. The ingot was re-melted 5 times to ensure chemical homogeneity. The ribbons were prepared by re-melting the ingot and then injecting the melt onto the surface of Cu roller at the wheel speeds of 8 m/s and 32 m/s, respectively. Under certain conditions, wheel speed is proportional to cooling rate, so herein wheel speed directly presents the cooling rate of the melt. The structure was examined by X-ray diffraction (XRD) with Cu-Ka radiation. Thermal stability was studied by differential scanning calorimetry (DSC) at a heating rate of 20 °C/min. The ribbons were sealed in evacuated quartz capsules and annealed at isothermal and continuous heating conditions, respectively for stress-relief and crystallization of the as quenched ribbons. Stress-relief annealing was conducted by isothermal heating at 350 °C (50 °C before the first initial crystallization temperature) for 10 min. Crystallization annealing was also conducted by continuous heating from room temperature to 450 °C, 537 °C, 657 °C and 750 °C, respectively, at a heating rate of 20 °C/min, and then quenched by water. Bs was
R. Wei et al. / Journal of Magnetism and Magnetic Materials 435 (2017) 184–186
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Fig. 1 shows the XRD patterns of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 asspun ribbons at different cooling rates. It can be seen that the ribbon spun at high cooling rate of 32 m/s exhibits a broad diffraction peak without any distinct crystalline peaks, indicating a fully amorphous phase structure. Sharp Bragg peaks corresponding to FCC phases were observed in the ribbon at low cooling rate of 8 m/s. In addition, a superlattice peak was also found in the ribbon obtained at low cooling rate, indicating that a minor order phase might be formed [11,12]. Therefore, Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy can form amorphous phases and solid solution phases (high entropy crystal structure) through controlling cooling rate. In principle any solid solution alloy can become amorphous if sufficiently high cooling rate is given [13]. However, most of high entropy amorphous alloy fail to form solid solution phase [14– 16]. Usually, three parameters were used to characterize the collective behavior of the constituent elements in HEAs, i.e. the atomic size difference (d), the mixing enthalpy (DHmix) and the mixing entropy (DSmix) [2,6]. Their calculation formula and element parameters can be found in Ref [2]. These parameters govern the formation of solid solution phases or amorphous phases of HEAs [2]. Guo and Liu found that solid solution phases only form when d, DHmix and DSmix simultaneously satisfy 0 d 8.5, 22 DHmix 7 kJ/mol and 11 DSmix 19.5 J/Kmol [2]. The d, DHmix and DSmix of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy was calculated to be 11.2, 20.9 kJ/mol and 12.6 J/Kmol respectively. It is obviously that the d of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy does not satisfy Guo’s results. This may be because that Guo’s results are based on HEAs mainly containing metal elements. The present HEA contains many non-metallic elements. The atomic radius of B and P are much smaller than that of Fe, Co and Ni. Therefore, B and P can exist in the interstitial position of FCC crystal lattice formed by FeCoNiSi [17]. In addition, the d, DHmix and DSmix of the present HEA satisfy amorphous phases form region of Guo’s results [2], i.e. d 9, 35 DHmix 8.kJ/mol and 7 DSmix 14 J/Kmol. It is worth noting that Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA was developed from Fe84Si4.5B8.5P3 amorphous alloy by adding Co and Ni [18]. Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy can form amorphous ribbon is also in
line with expectations according to the similar-atom substitution criteria about amorphous formation ability [19]. Fig. 2 shows the hysteresis loops of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA with different phase structure. It can be seen that both the amorphous phase and solid solution phase exhibit a typical soft magnetic characteristic. The Bs (1.07 T) of the amorphous phase is larger than that (1.0 T) of the solid solution phase. However, the Hc (4 A/m) of amorphous phase is significantly smaller than that (168 A/m) of the solid solution phase. It was report that Bs is primarily determined by the composition and atomic-level structures, but less sensitive to grain size [7]. It was found that phase transition from FCC to BCC (low symmetry) for FeCoNi(CuAl)0.8 HEA, resulting in a substantial increase in the Bs [5]. In addition, it is known that, unlike ferromagnetic BCC Fe, the ferromagnetism of Fe atoms is counteracted if arranged in a closely packed configuration, such as FCC lattice [20]. Compared to amorphous alloy without symmetry, the low Bs of solid solution alloy is caused by the fact that the high symmetry of the FCC lattice could partially neutralize atomic magnetic moment. Different from the Bs, the Hc is sensitive to the grain size [21], and thus the larger grain size (in micron scale) of HEA, generally results in higher Hc [7,19]. Fig. 3 shows the DSC curves of the present HEA alloy with amorphous structure. Two separated exothermic peaks can be seen on the curve, indicating that the crystallization takes place through two stages. Interestingly, there has an endothermic platform after the final crystallization, which indicates phase transition occurs during this stage. In order to clarify the crystallization phases, crystallization annealing was conducted by continuously heating from room temperature to 450 °C, 537 °C, 657 °C and 750 °C, respectively, as indicated by the arrow on the DSC curve. Fig. 4 shows the corresponding XRD patterns of the continuously annealed HEA alloy. Crystallization products of the amorphous phase, i.e. annealed at 450 °C or 537 °C, is only composed of solid solution phase including main FCC and a small amount of BCC. As mentioned above (Fig. 1), only FCC phase and a minor order phase were obtained by directly cooling the melt. Therefore, regardless of amorphous crystallization or direct cooling the melt, the main crystallization and phase transition product are both FCC phase. The appearance of BCC phase after crystallization of amorphous phase may be associated with the configurational entropy [9]. It was reported that the crystallization products of FeSiBAlNi amorphous alloy contain FCC phase and BCC phase [22]. Furthermore, it was found that annealing can lead to the occurrence of phase transition from FCC to BCC phase for FeCoNi(CuAl)0.8 HEA [5]. However, the mechanism of phase evolution of the present
Fig. 1. X-ray diffraction patterns of as-cast Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy at cooling rate of 8 m/s and 32 m/s.
Fig. 2. Hysteresis loops of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA with different phase structure.
measured by vibrating sample magnetometer (VSM) under a maximum applied field of 800 kA/m. Hc was measured with B-H loop tracer.
3. Results and discussion
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BCC (from 657 °C to 750 °C). This is similar to the transformation process of pure Fe from low temperature BCC to medium temperature FCC, and then to high temperature BCC. However, the phase transition mechanism in the present HEA needs to be further studied in the future work. 4. Conclusion Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA with amorphous phase and FCC solid solution phase were successfully developed respectively by melt spinning method. Compared to the solid solution phase, the amorphous phase exhibits better soft magnetic properties. Interestingly, the amorphous phase can be transformed into solid solution phase by annealing treatment, the BCC phase into FCC phase, and then into BCC phase was found in this HEA. Acknowledgements Fig. 3. DSC curves of the Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy at cooling rate of 32 m/s.
This work was financially supported by the Zhengzhou Project of research and development of new industry (No. 153PXXCY181), the Young Teacher Special Fund of Zhengzhou University (No. 51099064) and the National Nature Science Foundation of China (No. 51401160). References
Fig. 4. The corresponding XRD patterns of the continuously annealed HEA at different temperature.
HEA needs to be further study. The HEA annealed at 657 °C or 750 °C are also mainly composed of solid solution phase FCC and BCC, only a small amount of (FeCoNi)B phase was formed. In order to illustrate the phase transformation process around endothermic platform temperature range, the intensities of XRD peaks are used to estimate the relative volume fraction of the FCC and BCC phases. The volume fraction ratio of FCC/BCC in the annealed alloys at 450 °C, 537 °C, 657 °C and 750 °C is 19, 2.9, 25 and 2.6 respectively. So, the phase change process is a transform from BCC to FCC (from 537 °C to 657 °C), and then from FCC to
[1] J.W. Yeh, S.K. Chen, S.J. Lin, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau, S.Y. Chang, Adv. Eng. Mater. 6 (2004) 299–303. [2] S. Guo, C.T. Liu, Prog. Nat. Sci. 21 (2011) 433–446. [3] J. Wang, Z. Zheng, J. Xu, Y. Wang, J. Magn. Magn. Mater. 355 (2014) 58–64. [4] L. Ma, C. Li, Y. Jiang, J. Zhou, L. Wang, F. Wang, T. Cao, Y. Xue, J. Alloy. Compd. 694 (2017) 61–67. [5] Q. Zhang, H. Xu, X.H. Tan, X.L. Hou, S.W. Wu, G.S. Tan, L.Y. Yu, J. Alloy. Compd. 693 (2017) 1061–1067. [6] Y. Zhang, T.T. Zuo, Z. Tang, M.C. Gao, K.A. Dahmen, P.K. Liaw, Z.P. Lu, Prog. Mater Sci. 61 (2014) 1–93. [7] Y. Zhang, T. Zuo, Y. Cheng, P.K. Liaw, Sci. Rep. 3 (2013) 1455. [8] J. Li, W. Jia, J. Wang, H. Kou, D. Zhang, E. Beaugnon, Mater. Des. 95 (2016) 183– 187. [9] G. Anand, R. Goodall, C.L. Freeman, Scr. Mater. 124 (2016) 90–94. [10] A. Takeuchi, J. Wang, N. Chen, W. Zhang, Y. Yokoyama, K. Yubuta, S. Zhu, Mater. Trans. 54 (2013) 776–782. [11] P. Li, A. Wang, C.T. Liu, J. Alloy. Compd. 694 (2017) 55–60. [12] S. Guo, C. Ng, C.T. Liu, J. Alloy. Compd. 557 (2013) 77–81. [13] M.H. Cohen, D. Amp, Turnbull, Nature 189 (1961) 131–132. [14] A. Takeuchi, N. Chen, T. Wada, Y. Yokoyama, H. Kato, A. Inoue, J.W. Yeh, Intermetallics 19 (2011) 1546–1554. [15] T. Qi, Y. Li, A. Takeuchi, G. Xie, H. Miao, W. Zhang, Intermetallics 66 (2015) 8– 12. [16] Y. Li, W. Zhang, T. Qi, J. Alloy. Compd. 693 (2017) 25–31. [17] T.T. Zuo, R.B. Li, X.J. Ren, Y. Zhang, J. Magn. Magn. Mater. 371 (2014) 60–68. [18] F.L. Kong, C.T. Chang, A. Inoue, E. Shalaan, F. Al-Marzouki, J. Alloy. Compd. 615 (2014) 163–166. [19] R. Li, S. Pang, C. Ma, T. Zhang, Acta Mater. 55 (2007) 3719–3726. [20] B. Huang, Y. Yang, A.D. Wang, Q. Wang, C.T. Liu, Intermetallics 84 (2017) 74– 81. [21] G. Herzer, Acta Mater. 61 (2013) 718–734. [22] X. Zhu, X. Zhou, S. Yu, C. Wei, J. Xu, Y. Wang, J. Magn. Magn. Mater. 430 (2017) 59–64.
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Effect of cooling rate on the phase structure and magnetic properties of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 high entropy alloy Ran Wei a, Huan Sun a, Chen Chen a, Zhenhua Han b, Fushan Li a,⇑ a b
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710068, China
a r t i c l e
i n f o
Article history: Received 22 January 2017 Received in revised form 24 March 2017 Accepted 7 April 2017 Available online 9 April 2017 Keywords: High entropy alloy Amorphous alloys Soft magnetic properties Annealing Phase transformation
a b s t r a c t The effect of cooling rate on phase structure and magnetic properties of the Fe26.7Co28.5Ni28.5Si4.6B8.7P3 high entropy alloy (HEA) was investigated. The HEA forms into amorphous phase by melt spinning method at high cooling rate and FCC solid solution phase at low cooling rate. The soft magnetic properties of the amorphous phase (saturation magnetization Bs of 1.07T and coercivity Hc of 4 A/m) are better than that of the solid solution phase (Bs of 1.0 T and Hc of 168 A/m). In order to study the phase evolution of the present HEA, anneal experiments were conducted. It is found that crystallization products of amorphous phase are solid solution phase which constitute much of FCC and a small amount of BCC. BCC phase transforms into FCC phase, and then into BCC phase with the increase of annealing temperature. Ó 2017 Elsevier B.V. All rights reserved.
1. Introduction High entropy alloys (HEAs) are a class of alloys with multiprincipal elements at equimolar ratio or with concentrations between 5 and 35 at.% [1]. Some HEAs have been reported to exhibit simple crystal structures such as body-centred cubic (BCC) or face-centred cubic (FCC), some other HEAs can form amorphous structures [2]. HEAs are receiving much attention for their unique structures as well as excellent performances [3–7]. Recently, many researches are conducted to understand their phase evolution, and thus to design microstructural [4,8,9]. BCC phase was obtained in CoCrFeNi HEA by supercooling method to enhance its mechanical properties [8]. By tailoring the alloy composition of AlxSi0.2CrCoFeNiCu1 x HEAs, rapid cooling rate can promote the formation of FCC or BCC in these HEAs, and then different mechanical properties were obtained [4]. Al0.5TiZrPdCuNi HEA can form single amorphous phase by melt spinning method at high cooling rate and single BCC solid solution phase by copper-mold casting at low cooling rate [10]. However, the effects of cooling rate on phase structure, especially magnetic properties of HEAs, leading to formation of amorphous phase or simple solid solution phase, are still limited. In this work, Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA constituted only by ferromagnetic elements and metalloids which favors good soft ⇑ Corresponding author. E-mail address: [email protected] (F. Li). http://dx.doi.org/10.1016/j.jmmm.2017.04.017 0304-8853/Ó 2017 Elsevier B.V. All rights reserved.
magnetic properties, with amorphous phase and simple solid solution phase were prepared respectively by melt-spinning method. The effect of cooling rate on the phase structure and magnetic properties of the present HEA was discussed in detail. The phase evolution of the amorphous phase was studied.
2. Experimental procedure Alloy ingot of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 (at.%) was prepared by induction melting of industrial pure materials under argon atmosphere. The ingot was re-melted 5 times to ensure chemical homogeneity. The ribbons were prepared by re-melting the ingot and then injecting the melt onto the surface of Cu roller at the wheel speeds of 8 m/s and 32 m/s, respectively. Under certain conditions, wheel speed is proportional to cooling rate, so herein wheel speed directly presents the cooling rate of the melt. The structure was examined by X-ray diffraction (XRD) with Cu-Ka radiation. Thermal stability was studied by differential scanning calorimetry (DSC) at a heating rate of 20 °C/min. The ribbons were sealed in evacuated quartz capsules and annealed at isothermal and continuous heating conditions, respectively for stress-relief and crystallization of the as quenched ribbons. Stress-relief annealing was conducted by isothermal heating at 350 °C (50 °C before the first initial crystallization temperature) for 10 min. Crystallization annealing was also conducted by continuous heating from room temperature to 450 °C, 537 °C, 657 °C and 750 °C, respectively, at a heating rate of 20 °C/min, and then quenched by water. Bs was
R. Wei et al. / Journal of Magnetism and Magnetic Materials 435 (2017) 184–186
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Fig. 1 shows the XRD patterns of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 asspun ribbons at different cooling rates. It can be seen that the ribbon spun at high cooling rate of 32 m/s exhibits a broad diffraction peak without any distinct crystalline peaks, indicating a fully amorphous phase structure. Sharp Bragg peaks corresponding to FCC phases were observed in the ribbon at low cooling rate of 8 m/s. In addition, a superlattice peak was also found in the ribbon obtained at low cooling rate, indicating that a minor order phase might be formed [11,12]. Therefore, Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy can form amorphous phases and solid solution phases (high entropy crystal structure) through controlling cooling rate. In principle any solid solution alloy can become amorphous if sufficiently high cooling rate is given [13]. However, most of high entropy amorphous alloy fail to form solid solution phase [14– 16]. Usually, three parameters were used to characterize the collective behavior of the constituent elements in HEAs, i.e. the atomic size difference (d), the mixing enthalpy (DHmix) and the mixing entropy (DSmix) [2,6]. Their calculation formula and element parameters can be found in Ref [2]. These parameters govern the formation of solid solution phases or amorphous phases of HEAs [2]. Guo and Liu found that solid solution phases only form when d, DHmix and DSmix simultaneously satisfy 0 d 8.5, 22 DHmix 7 kJ/mol and 11 DSmix 19.5 J/Kmol [2]. The d, DHmix and DSmix of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy was calculated to be 11.2, 20.9 kJ/mol and 12.6 J/Kmol respectively. It is obviously that the d of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy does not satisfy Guo’s results. This may be because that Guo’s results are based on HEAs mainly containing metal elements. The present HEA contains many non-metallic elements. The atomic radius of B and P are much smaller than that of Fe, Co and Ni. Therefore, B and P can exist in the interstitial position of FCC crystal lattice formed by FeCoNiSi [17]. In addition, the d, DHmix and DSmix of the present HEA satisfy amorphous phases form region of Guo’s results [2], i.e. d 9, 35 DHmix 8.kJ/mol and 7 DSmix 14 J/Kmol. It is worth noting that Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA was developed from Fe84Si4.5B8.5P3 amorphous alloy by adding Co and Ni [18]. Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy can form amorphous ribbon is also in
line with expectations according to the similar-atom substitution criteria about amorphous formation ability [19]. Fig. 2 shows the hysteresis loops of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA with different phase structure. It can be seen that both the amorphous phase and solid solution phase exhibit a typical soft magnetic characteristic. The Bs (1.07 T) of the amorphous phase is larger than that (1.0 T) of the solid solution phase. However, the Hc (4 A/m) of amorphous phase is significantly smaller than that (168 A/m) of the solid solution phase. It was report that Bs is primarily determined by the composition and atomic-level structures, but less sensitive to grain size [7]. It was found that phase transition from FCC to BCC (low symmetry) for FeCoNi(CuAl)0.8 HEA, resulting in a substantial increase in the Bs [5]. In addition, it is known that, unlike ferromagnetic BCC Fe, the ferromagnetism of Fe atoms is counteracted if arranged in a closely packed configuration, such as FCC lattice [20]. Compared to amorphous alloy without symmetry, the low Bs of solid solution alloy is caused by the fact that the high symmetry of the FCC lattice could partially neutralize atomic magnetic moment. Different from the Bs, the Hc is sensitive to the grain size [21], and thus the larger grain size (in micron scale) of HEA, generally results in higher Hc [7,19]. Fig. 3 shows the DSC curves of the present HEA alloy with amorphous structure. Two separated exothermic peaks can be seen on the curve, indicating that the crystallization takes place through two stages. Interestingly, there has an endothermic platform after the final crystallization, which indicates phase transition occurs during this stage. In order to clarify the crystallization phases, crystallization annealing was conducted by continuously heating from room temperature to 450 °C, 537 °C, 657 °C and 750 °C, respectively, as indicated by the arrow on the DSC curve. Fig. 4 shows the corresponding XRD patterns of the continuously annealed HEA alloy. Crystallization products of the amorphous phase, i.e. annealed at 450 °C or 537 °C, is only composed of solid solution phase including main FCC and a small amount of BCC. As mentioned above (Fig. 1), only FCC phase and a minor order phase were obtained by directly cooling the melt. Therefore, regardless of amorphous crystallization or direct cooling the melt, the main crystallization and phase transition product are both FCC phase. The appearance of BCC phase after crystallization of amorphous phase may be associated with the configurational entropy [9]. It was reported that the crystallization products of FeSiBAlNi amorphous alloy contain FCC phase and BCC phase [22]. Furthermore, it was found that annealing can lead to the occurrence of phase transition from FCC to BCC phase for FeCoNi(CuAl)0.8 HEA [5]. However, the mechanism of phase evolution of the present
Fig. 1. X-ray diffraction patterns of as-cast Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy at cooling rate of 8 m/s and 32 m/s.
Fig. 2. Hysteresis loops of Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA with different phase structure.
measured by vibrating sample magnetometer (VSM) under a maximum applied field of 800 kA/m. Hc was measured with B-H loop tracer.
3. Results and discussion
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BCC (from 657 °C to 750 °C). This is similar to the transformation process of pure Fe from low temperature BCC to medium temperature FCC, and then to high temperature BCC. However, the phase transition mechanism in the present HEA needs to be further studied in the future work. 4. Conclusion Fe26.7Co28.5Ni28.5Si4.6B8.7P3 HEA with amorphous phase and FCC solid solution phase were successfully developed respectively by melt spinning method. Compared to the solid solution phase, the amorphous phase exhibits better soft magnetic properties. Interestingly, the amorphous phase can be transformed into solid solution phase by annealing treatment, the BCC phase into FCC phase, and then into BCC phase was found in this HEA. Acknowledgements Fig. 3. DSC curves of the Fe26.7Co28.5Ni28.5Si4.6B8.7P3 alloy at cooling rate of 32 m/s.
This work was financially supported by the Zhengzhou Project of research and development of new industry (No. 153PXXCY181), the Young Teacher Special Fund of Zhengzhou University (No. 51099064) and the National Nature Science Foundation of China (No. 51401160). References
Fig. 4. The corresponding XRD patterns of the continuously annealed HEA at different temperature.
HEA needs to be further study. The HEA annealed at 657 °C or 750 °C are also mainly composed of solid solution phase FCC and BCC, only a small amount of (FeCoNi)B phase was formed. In order to illustrate the phase transformation process around endothermic platform temperature range, the intensities of XRD peaks are used to estimate the relative volume fraction of the FCC and BCC phases. The volume fraction ratio of FCC/BCC in the annealed alloys at 450 °C, 537 °C, 657 °C and 750 °C is 19, 2.9, 25 and 2.6 respectively. So, the phase change process is a transform from BCC to FCC (from 537 °C to 657 °C), and then from FCC to
[1] J.W. Yeh, S.K. Chen, S.J. Lin, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau, S.Y. Chang, Adv. Eng. Mater. 6 (2004) 299–303. [2] S. Guo, C.T. Liu, Prog. Nat. Sci. 21 (2011) 433–446. [3] J. Wang, Z. Zheng, J. Xu, Y. Wang, J. Magn. Magn. Mater. 355 (2014) 58–64. [4] L. Ma, C. Li, Y. Jiang, J. Zhou, L. Wang, F. Wang, T. Cao, Y. Xue, J. Alloy. Compd. 694 (2017) 61–67. [5] Q. Zhang, H. Xu, X.H. Tan, X.L. Hou, S.W. Wu, G.S. Tan, L.Y. Yu, J. Alloy. Compd. 693 (2017) 1061–1067. [6] Y. Zhang, T.T. Zuo, Z. Tang, M.C. Gao, K.A. Dahmen, P.K. Liaw, Z.P. Lu, Prog. Mater Sci. 61 (2014) 1–93. [7] Y. Zhang, T. Zuo, Y. Cheng, P.K. Liaw, Sci. Rep. 3 (2013) 1455. [8] J. Li, W. Jia, J. Wang, H. Kou, D. Zhang, E. Beaugnon, Mater. Des. 95 (2016) 183– 187. [9] G. Anand, R. Goodall, C.L. Freeman, Scr. Mater. 124 (2016) 90–94. [10] A. Takeuchi, J. Wang, N. Chen, W. Zhang, Y. Yokoyama, K. Yubuta, S. Zhu, Mater. Trans. 54 (2013) 776–782. [11] P. Li, A. Wang, C.T. Liu, J. Alloy. Compd. 694 (2017) 55–60. [12] S. Guo, C. Ng, C.T. Liu, J. Alloy. Compd. 557 (2013) 77–81. [13] M.H. Cohen, D. Amp, Turnbull, Nature 189 (1961) 131–132. [14] A. Takeuchi, N. Chen, T. Wada, Y. Yokoyama, H. Kato, A. Inoue, J.W. Yeh, Intermetallics 19 (2011) 1546–1554. [15] T. Qi, Y. Li, A. Takeuchi, G. Xie, H. Miao, W. Zhang, Intermetallics 66 (2015) 8– 12. [16] Y. Li, W. Zhang, T. Qi, J. Alloy. Compd. 693 (2017) 25–31. [17] T.T. Zuo, R.B. Li, X.J. Ren, Y. Zhang, J. Magn. Magn. Mater. 371 (2014) 60–68. [18] F.L. Kong, C.T. Chang, A. Inoue, E. Shalaan, F. Al-Marzouki, J. Alloy. Compd. 615 (2014) 163–166. [19] R. Li, S. Pang, C. Ma, T. Zhang, Acta Mater. 55 (2007) 3719–3726. [20] B. Huang, Y. Yang, A.D. Wang, Q. Wang, C.T. Liu, Intermetallics 84 (2017) 74– 81. [21] G. Herzer, Acta Mater. 61 (2013) 718–734. [22] X. Zhu, X. Zhou, S. Yu, C. Wei, J. Xu, Y. Wang, J. Magn. Magn. Mater. 430 (2017) 59–64.