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Solid state phase equilibria in the Fe–Pt–Dy ternary system at 900 °C
Journal of Alloys and Compounds 427 (2007) 130–133
Solid state phase equilibria in the Fe–Pt–Dy ternary system at 900 ◦C Ma Lei a,b,∗ , Gu Zhengfei a , Zhong Xiaping b , Cheng Gang a , Zhou Bo a , Xu Chengfu a a
Department of Information Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China b Department of Materials and Chemistry Engineering, Guilin University of Technology, Guilin 541004, China Received 27 January 2006; received in revised form 25 February 2006; accepted 27 February 2006 Available online 18 April 2006
Abstract The solid state phase equilibria in the Fe–Pt–Dy ternary system at 900 ◦ C (Dy ≤ 75 at.%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. It is found that the 900 ◦ C isothermal section consists of 18 single-phase regions, 33 two-phase regions and 16 three-phase regions. At 900 ◦ C, it is observed that the maximum solid solubility of Pt in Fe2 Dy and ␣-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively. The binary phase Fe5 Dy was not observed. The existence of DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt compounds is confirmed and the maximum solubility of Fe in them is below 1 at.% Fe; the maximum solubility of Dy in ␣-(Fe, Pt), ␥-(Fe, Pt), FePt, FePt3 and (Pt, Fe) (the solid solution of Fe in Pt) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively. © 2006 Elsevier B.V. All rights reserved. Keywords: Transition metal compounds; Rare earth compounds; Phase diagram; Crystal structure; X-ray diffraction
1. Introduction The Fe–Pt, Dy–Pt and Fe–Dy binary systems bounding the Fe–Pt–Dy ternary system have been widely studied. It has been reported that the three binary compounds Fe3 Pt, FePt and FePt3 exist in the Fe–Pt binary system, four binary compounds Fe17 Dy2 , Fe23 Dy6 , Fe3 Dy and Fe2 Dy in the Fe–Dy binary system and nine binary compounds DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt in the Dy–Pt binary system [1]. Crystallographic data for these binary compounds of the Fe–Pt, Fe–Dy and Dy–Pt systems are collected in Table 1 [1–7]. According to Ref. [8], the binary phase Fe5 Dy (CaCu5 structure type, P6/mmm, a = 0.490, c = 0.410) exists. However, it is not reported in later literature [1]. The Dy–Pt binary phase diagram constructed largely on the basis of the presumed similarity with the Er–Pt system is reported in the literature [1], and determination of partial phases of Dy–Pt system in the 0–50 at.% Pt composition range is reported in recent Ref. [5]; all the intermediate phases form through peritectic reactions, with the exception
∗
Corresponding author. E-mail address: [email protected] (M. Lei).
0925-8388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2006.02.063
of the DyPt and DyPt3 that melt congruently. The ternary diagram and ternary compounds of the Fe–Pt–Dy system were not reported. The results of the investigation of the phase relations in the Fe–Pt–Dy system at 900 ◦ C are given in the present work. 2. Experimental details The solid state phase equilibria of Fe–Pt–Dy system at 900 ◦ C were constructed by using the results of the X-ray phase analysis of 62 samples, as well as those obtained from scanning electron microscopy and energy dispersion spectroscopy on some selected samples. All the samples were prepared by arc-melting of pure metals (the purity of the ingredients is better than 99.9 wt.%) on a water-cooled copper hearth under a purified argon atmosphere. They were remelted four times to accomplish homogeneity. The mass losses after the melting were less than 0.5 wt.%. The samples were sealed in quartz tubes pre-evacuated and refilled some purified argon and annealed at 900 ◦ C for 15 days. After annealing, the ampoules with samples were quenched in ice water. The brittleness samples were ground into powders in ceramic mortar for X-ray diffraction with Si as the internal standard. A few toughness samples were pressed into slices (7 mm × 3 mm × 1 mm) and sealed again in quartz tubes, then annealed under the protection of purified argon at 900 ◦ C for 15 days to eliminate the stress and quenched in ice water for X-ray diffraction. Phase analysis was carried out using X-ray diffraction (Cu K␣ radiation), scanning electron microscopy and energy dispersion spectroscopy techniques.
M. Lei et al. / Journal of Alloys and Compounds 427 (2007) 130–133
131
Table 1 Crystallographic parameters for the binary compounds of the Fe–Pt, Dy–Pt and Fe–Dy systems Compounds
Fe3 Pt Fe3 Pt Fe3 Pt FePt FePt FePt FePt3 Dy3 Pt Dy3 Pt Dy2 Pt Dy2 Pt Dy5 Pt3 Dy5 Pt3 Dy5 Pt4 Dy5 Pt4 DyPt DyPt DyPt Dy3 Pt4 DyPt2 DyPt3 DyPt5 Fe17 Dy2 Fe23 Dy6 Fe3 Dy Fe2 Dy
Structure type
Space group
AuCu3 Cu W AuCu3 AuCu Pa AuCu3 CFe3 Fe3 C Co2 Si Co2 Si Mn5 Si3 Mn5 Si3 Ge4 Sm5 Ge4 Sm5 BFe FeB FeB Pd4 Pu3 Cu2 Mg AuCu3 – Ni17 Th2 Mn23 Th6 Be3 Nb Cu2 Mg
¯ Pm3m ¯ Fm3m ¯ Im3m ¯ Pm3m P4/mmm I4/mmm ¯ Pm3m Pnma oP16 Pnma oP12 P63 /mcm hP16 Pnma oP36 Pnma Pnma oP8 R3¯ ¯ Fd 3m ¯ Pm3m O*72 P63 /mmc ¯ Fm3m ¯ R3m ¯ Fd 3m
3. Results and discussion 3.1. Phase analysis 3.1.1. Binary Fe–Dy system There is an argument whether the phase Fe5 Dy exists or not in binary Fe–Dy system. According to Ref. [8], the binary phase Fe5 Dy exists. However, in terms of Ref. [1], it does not form in binary Fe–Dy system. For this reason, we prepared the sample of the alloy corresponding to the composition 83.3 at.% Fe. The X-ray diffraction data, shown in Fig. 1, demonstrate that the pattern is only the overlapping ones of Fe17 Dy2 and Fe23 Dy6 , which indicates that the Fe5 Dy compound does not exist indeed in our experimental condition. This result agrees well with that reported in Ref. [1]. For Fe2 Dy, an important giant magnetostrictive material, we have prepared a series of samples in the phase range including Fe2 Dy compound of Fe–Pt–Dy ternary system. The X-ray diffraction data of Fe63 Pt2 Dy35 and Fe60 Pt5 Dy35 , shown in Fig. 2, indicate that they are single-phases of Fe2 Dy, moreover, the scanning electron micrograph (Fig. 3) also clearly shows that it is only one phase. From these data, it follows Fe2 Dy phase extends to about 5 at.% Pt in Fe–Pt–Dy system in our experimental condition. 3.1.2. Binary Dy–Pt system In the literature [1], it is reported that the Dy–Pt binary phase diagram was constructed largely on the basis of the pre-
Lattice parameters (nm)
Refs.
a
b
c
0.3727 0.3723 0.2969 0.3841 0.4000 0.3905 0.3872 0.70493 0.70421 0.71017 0.70955 0.83674 0.8359 0.74525 0.7470 0.54661 0.6983 0.69736 1.3107 0.759667 0.407232 0.5237 0.8453 1.210 0.5125 0.7328
– – – – – – – 0.94855 0.94714 0.47474 0.47392 – – 1.45338 1.4560 0.445313 0.4478 0.44796 – – – 0.9098 – – – –
– – – – 0.3672 0.3735 – 0.64173 0.64215 0.87318 0.87301 0.62107 0.6233 0.75265 0.7543 0.71189 0.5544 0.55391 0.5673 – – 2.647 0.8287 – 2.4578 –
[1,2] [1,2] [1,2] [1,2] [1,2] [1,2] [1,2] [3] [5] [3] [5] [3] [5] [3] [5] [3] [4] [5] [3] [3] [3] [6,7] [3,4] [3,4] [3,4] [3,4]
sumed similarity to the Er–Pt system, in which there were nine intermetallic compounds present. It has been confirmed in Ref. [5] that Dy3 Pt, Dy2 Pt, Dy5 Pt3 , and Dy5 Pt4 form through peritectic reactions, while DyPt melts congruently at 1520 ◦ C. In our experiments, Dy3 Pt, Dy2 Pt, Dy5 Pt3 , Dy5 Pt4 , DyPt, Dy3 Pt4 , DyPt2 , DyPt3 and DyPt5 are found to be present at 900 ◦ C. An example of X-ray diffraction obtained for the Dy3 Pt4 compound is shown in Fig. 4. It suggests that the phase Dy3 Pt4 still exists in the Fe–Pt–Dy ternary system, which is different from the phase Pr3 Pt4 that is unstable and decomposes into the two neighboring
Fig. 1. XRD pattern of the alloy corresponding to the composition 83.3 at.% Fe annealed at 900 ◦ C.
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compounds PrPt and PrPt2 with more than 1 at.% Fe [9]. The reason for this may be due to the fact that Dy is heavy rare earth, while Pr is light rare earth and the atomic radius of Dy is less than that of Pr. 3.2. Solid solubility
Fig. 2. The XRD patterns of Fe60 Pt5 Dy35 (top part) and Fe63 Pt2 Dy35 (bottom part) alloys annealed at 900 ◦ C.
At 900 ◦ C, by means of X-ray diffraction, differential thermal analysis, scanning electron microscopy and energy dispersion spectroscopy techniques, we have observed that the maximum solid solubility of Pt in Fe2 Dy and ␣-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively; the maximum solid solubility of Dy in ␣-(Fe, Pt), ␥-(Fe, Pt), FePt, FePt3 and (Pt, Fe) (the solid solution of Fe in Pt) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively; the maximum solid solubility of Fe in DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt is below 1 at.% Fe. 3.3. Isothermal section at 900 ◦ C By comparing and analyzing the X-ray diffraction patterns of 62 samples, together with scanning electron microscopy and energy dispersion spectroscopy on some of the selected samples, we have identified the phase components of each sample (in Table 2). According to these results, the solid state phase equilibria of Fe–Pt–Dy system at 900 ◦ C (Dy ≤ 75 at.%) was determined. The 900 ◦ C isothermal section, shown in Fig. 5, consists of 18 single-phase regions, 33 two-phase regions and 16 three-phase regions.
Table 2 Identification of phase for the ternary alloy
Fig. 3. SEM micrograph of Fe60 Pt5 Dy35 sample annealed at 900 ◦ C.
Fig. 4. Observed XRD pattern of Fe10 Pt50 Dy40 alloy annealed at 900 ◦ C.
Samples
Ternary alloys
Phase components
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
Fe35 Pt15 Dy50 Fe41 Pt15 Dy44 Fe58 Pt10 Dy32 Fe60 Pt10 Dy30 Fe63 Pt2 Dy35 Fe63 Pt5 Dy32 Fe70 Pt10 Dy20 Fe70 Pt15 Dy15 Fe92 Pt5 Dy3 Fe98 Pt1 Dy1 Fe50 Pt30 Dy20 Fe55 Pt30 Dy15 Fe60 Pt30 Dy10 Fe66 Pt31 Dy3 Fe56 Pt40 Dy4 Fe52 Pt44 Dy4 Fe10 Pt50 Dy40 Fe40 Pt51 Dy9 Fe44 Pt51 Dy5 Fe47 Pt51 Dy2 Fe40 Pt58 Dy2 Fe30 Pt67 Dy3 Fe23 Pt75 Dy2 Fe17 Pt80 Dy3 Fe6 Pt92 Dy2
Fe2 Dy + Dy3 Pt + Dy2 Pt Fe2 Dy + Dy5 Pt3 Fe23 Dy6 + Dy5 Pt3 Fe23 Dy6 + Dy5 Pt3 + Dy5 Pt4 Fe2 Dy Fe3 Dy + Fe2 Dy + Dy5 Pt3 Fe17 Dy2 + Dy5 Pt4 ␣-Fe + DyPt ␣-Fe + Dy3 Pt4 ␣-Fe ␣-Fe + Dy3 Pt4 + DyPt2 ␣-Fe + DyPt2 ␥-(Fe, Pt) + DyPt2 ␥-(Fe, Pt) + FePt + DyPt2 ␥-(Fe, Pt) + FePt + DyPt2 FePt + DyPt2 ␣-Fe + DyPt + Dy3 Pt4 FePt + DyPt2 FePt + DyPt2 + DyPt3 FePt + DyPt3 + FePt3 FePt + DyPt3 + FePt3 FePt3 + DyPt3 FePt3 + DyPt3 FePt3 + DyPt5 + Pt Pt + DyPt5
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the disparity is not clear and further detailed characterization is required. 4. Conclusion
Fig. 5. Isothermal section of the phase diagram of the Fe–Pt–Dy ternary system at 900 ◦ C.
Eighteen single-phase regions are ␣(␣-Fe), (␥-(Fe, Pt)), ␥(FePt), ␦(FePt3 ), (Pt), (DyPt5 ), (DyPt3 ), (DyPt2 ), (Dy3 Pt4 ), (DyPt), (Dy5 Pt4 ), (Dy5 Pt3 ), (Dy2 Pt), (Dy3 Pt), о(Fe2 Dy), (Fe3 Dy), (Fe23 Dy6 ) and (Fe17 Dy2 ). Thirty-three two-phase regions are ␣ + ,  + ␥, ␥ + ␦, ␦ + , + , + , + , + , + , + , + , + , + , + о, о + , о + , о + , + , + , + , + , + , + , + , + ␣, ␣ + , ␣ + , ␣ + ,  + , ␥ + , ␥ + , ␦ + and ␦ + . Sixteen three-phase regions are о + + , о + + , о + + , + + , + + , + + , + + , + + ␣, ␣ + + , ␣ + + , ␣ + + ,  + + ␥, ␥ + + , ␥ + + ␦, ␦ + + and ␦ + + . Compared with Fe–Pt–Pr system [9], it is observed in the 900 ◦ C isothermal section that the DyPt5 compound co-exists with the FePt3 instead of FePt in equilibrium condition, which is different from PrPt5 (CaCu5 structure type). The reason for this may be due to the fact that Dy (heavy rare earth) and Pr (light rare earth) have different Pauling and atomic radius, and the structure type of FePt3 (AuCu3 structure type) is different with that of FePt (AuCu structure type). The reason for
1. At 900 ◦ C, Dy3 Pt, Dy2 Pt, Dy5 Pt3 , Dy5 Pt4 , DyPt, Dy3 Pt4 , DyPt2 , DyPt3 and DyPt5 phases exist in Fe–Pt–Dy ternary system. The Dy3 Pt4 phase remains stable with the addition of Fe element. 2. The maximum solid solubility of Pt in Fe2 Dy and ␣-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively; the maximum solid solubility of Dy in ␣-(Fe, Pt), ␥-(Fe, Pt), FePt, FePt3 and (Pt, Fe) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively; the maximum solid solubility of Fe in DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt is below 1 at.% Fe. 3. The 900 ◦ C isothermal sections of the phase diagram of the Fe–Pt–Dy ternary system (Dy ≤ 75 at.%) consist of 18 single-phase regions, 33 two-phase regions and 16 threephase regions. The existence of any new ternary compounds was not observed. Acknowledgement This work was supported by the National Natural Science Foundation of China (authorized number: 50261002). References [1] T.B. Massalski (Ed.), Binary Alloy Phase Diagrams, second ed., ASM International, Materials Park, OH, 1990. [2] W. Claus, G. Nolze, Federal Institute for Materials Research and Testing Rudower Chaussee, Berlin, 2000. [3] P. Villars, L.D. Calvert, Pearson’s Handbook of Crystallographic Data for Intermetallic Phases, ASM International, Materials Park, OH, 1991. [4] Powder Diffraction File, International Center for Diffraction Data [M], Pennsylvania, 1993. [5] D. Maccio, F. Rosalbino, A. Saccone, S. Delfino, J. Alloys Compd. 391 (2005) 60–66. [6] B. Erdmann, C. Keller, J. Solid State Chem. 7 (1973) 40–48. [7] W. Bronger, J. Less-Common Met. 12 (1) (1967) 63–68. [8] K. Nassau, L.V. Cherry, W.E. Wallace, Phys. Chem. Solids 16 (1960) 123–130. [9] R. Jing, G. Zhengfei, J. Alloys Compd. 394 (2005) 211–214.
Solid state phase equilibria in the Fe–Pt–Dy ternary system at 900 ◦C Ma Lei a,b,∗ , Gu Zhengfei a , Zhong Xiaping b , Cheng Gang a , Zhou Bo a , Xu Chengfu a a
Department of Information Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China b Department of Materials and Chemistry Engineering, Guilin University of Technology, Guilin 541004, China Received 27 January 2006; received in revised form 25 February 2006; accepted 27 February 2006 Available online 18 April 2006
Abstract The solid state phase equilibria in the Fe–Pt–Dy ternary system at 900 ◦ C (Dy ≤ 75 at.%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. It is found that the 900 ◦ C isothermal section consists of 18 single-phase regions, 33 two-phase regions and 16 three-phase regions. At 900 ◦ C, it is observed that the maximum solid solubility of Pt in Fe2 Dy and ␣-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively. The binary phase Fe5 Dy was not observed. The existence of DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt compounds is confirmed and the maximum solubility of Fe in them is below 1 at.% Fe; the maximum solubility of Dy in ␣-(Fe, Pt), ␥-(Fe, Pt), FePt, FePt3 and (Pt, Fe) (the solid solution of Fe in Pt) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively. © 2006 Elsevier B.V. All rights reserved. Keywords: Transition metal compounds; Rare earth compounds; Phase diagram; Crystal structure; X-ray diffraction
1. Introduction The Fe–Pt, Dy–Pt and Fe–Dy binary systems bounding the Fe–Pt–Dy ternary system have been widely studied. It has been reported that the three binary compounds Fe3 Pt, FePt and FePt3 exist in the Fe–Pt binary system, four binary compounds Fe17 Dy2 , Fe23 Dy6 , Fe3 Dy and Fe2 Dy in the Fe–Dy binary system and nine binary compounds DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt in the Dy–Pt binary system [1]. Crystallographic data for these binary compounds of the Fe–Pt, Fe–Dy and Dy–Pt systems are collected in Table 1 [1–7]. According to Ref. [8], the binary phase Fe5 Dy (CaCu5 structure type, P6/mmm, a = 0.490, c = 0.410) exists. However, it is not reported in later literature [1]. The Dy–Pt binary phase diagram constructed largely on the basis of the presumed similarity with the Er–Pt system is reported in the literature [1], and determination of partial phases of Dy–Pt system in the 0–50 at.% Pt composition range is reported in recent Ref. [5]; all the intermediate phases form through peritectic reactions, with the exception
∗
Corresponding author. E-mail address: [email protected] (M. Lei).
0925-8388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2006.02.063
of the DyPt and DyPt3 that melt congruently. The ternary diagram and ternary compounds of the Fe–Pt–Dy system were not reported. The results of the investigation of the phase relations in the Fe–Pt–Dy system at 900 ◦ C are given in the present work. 2. Experimental details The solid state phase equilibria of Fe–Pt–Dy system at 900 ◦ C were constructed by using the results of the X-ray phase analysis of 62 samples, as well as those obtained from scanning electron microscopy and energy dispersion spectroscopy on some selected samples. All the samples were prepared by arc-melting of pure metals (the purity of the ingredients is better than 99.9 wt.%) on a water-cooled copper hearth under a purified argon atmosphere. They were remelted four times to accomplish homogeneity. The mass losses after the melting were less than 0.5 wt.%. The samples were sealed in quartz tubes pre-evacuated and refilled some purified argon and annealed at 900 ◦ C for 15 days. After annealing, the ampoules with samples were quenched in ice water. The brittleness samples were ground into powders in ceramic mortar for X-ray diffraction with Si as the internal standard. A few toughness samples were pressed into slices (7 mm × 3 mm × 1 mm) and sealed again in quartz tubes, then annealed under the protection of purified argon at 900 ◦ C for 15 days to eliminate the stress and quenched in ice water for X-ray diffraction. Phase analysis was carried out using X-ray diffraction (Cu K␣ radiation), scanning electron microscopy and energy dispersion spectroscopy techniques.
M. Lei et al. / Journal of Alloys and Compounds 427 (2007) 130–133
131
Table 1 Crystallographic parameters for the binary compounds of the Fe–Pt, Dy–Pt and Fe–Dy systems Compounds
Fe3 Pt Fe3 Pt Fe3 Pt FePt FePt FePt FePt3 Dy3 Pt Dy3 Pt Dy2 Pt Dy2 Pt Dy5 Pt3 Dy5 Pt3 Dy5 Pt4 Dy5 Pt4 DyPt DyPt DyPt Dy3 Pt4 DyPt2 DyPt3 DyPt5 Fe17 Dy2 Fe23 Dy6 Fe3 Dy Fe2 Dy
Structure type
Space group
AuCu3 Cu W AuCu3 AuCu Pa AuCu3 CFe3 Fe3 C Co2 Si Co2 Si Mn5 Si3 Mn5 Si3 Ge4 Sm5 Ge4 Sm5 BFe FeB FeB Pd4 Pu3 Cu2 Mg AuCu3 – Ni17 Th2 Mn23 Th6 Be3 Nb Cu2 Mg
¯ Pm3m ¯ Fm3m ¯ Im3m ¯ Pm3m P4/mmm I4/mmm ¯ Pm3m Pnma oP16 Pnma oP12 P63 /mcm hP16 Pnma oP36 Pnma Pnma oP8 R3¯ ¯ Fd 3m ¯ Pm3m O*72 P63 /mmc ¯ Fm3m ¯ R3m ¯ Fd 3m
3. Results and discussion 3.1. Phase analysis 3.1.1. Binary Fe–Dy system There is an argument whether the phase Fe5 Dy exists or not in binary Fe–Dy system. According to Ref. [8], the binary phase Fe5 Dy exists. However, in terms of Ref. [1], it does not form in binary Fe–Dy system. For this reason, we prepared the sample of the alloy corresponding to the composition 83.3 at.% Fe. The X-ray diffraction data, shown in Fig. 1, demonstrate that the pattern is only the overlapping ones of Fe17 Dy2 and Fe23 Dy6 , which indicates that the Fe5 Dy compound does not exist indeed in our experimental condition. This result agrees well with that reported in Ref. [1]. For Fe2 Dy, an important giant magnetostrictive material, we have prepared a series of samples in the phase range including Fe2 Dy compound of Fe–Pt–Dy ternary system. The X-ray diffraction data of Fe63 Pt2 Dy35 and Fe60 Pt5 Dy35 , shown in Fig. 2, indicate that they are single-phases of Fe2 Dy, moreover, the scanning electron micrograph (Fig. 3) also clearly shows that it is only one phase. From these data, it follows Fe2 Dy phase extends to about 5 at.% Pt in Fe–Pt–Dy system in our experimental condition. 3.1.2. Binary Dy–Pt system In the literature [1], it is reported that the Dy–Pt binary phase diagram was constructed largely on the basis of the pre-
Lattice parameters (nm)
Refs.
a
b
c
0.3727 0.3723 0.2969 0.3841 0.4000 0.3905 0.3872 0.70493 0.70421 0.71017 0.70955 0.83674 0.8359 0.74525 0.7470 0.54661 0.6983 0.69736 1.3107 0.759667 0.407232 0.5237 0.8453 1.210 0.5125 0.7328
– – – – – – – 0.94855 0.94714 0.47474 0.47392 – – 1.45338 1.4560 0.445313 0.4478 0.44796 – – – 0.9098 – – – –
– – – – 0.3672 0.3735 – 0.64173 0.64215 0.87318 0.87301 0.62107 0.6233 0.75265 0.7543 0.71189 0.5544 0.55391 0.5673 – – 2.647 0.8287 – 2.4578 –
[1,2] [1,2] [1,2] [1,2] [1,2] [1,2] [1,2] [3] [5] [3] [5] [3] [5] [3] [5] [3] [4] [5] [3] [3] [3] [6,7] [3,4] [3,4] [3,4] [3,4]
sumed similarity to the Er–Pt system, in which there were nine intermetallic compounds present. It has been confirmed in Ref. [5] that Dy3 Pt, Dy2 Pt, Dy5 Pt3 , and Dy5 Pt4 form through peritectic reactions, while DyPt melts congruently at 1520 ◦ C. In our experiments, Dy3 Pt, Dy2 Pt, Dy5 Pt3 , Dy5 Pt4 , DyPt, Dy3 Pt4 , DyPt2 , DyPt3 and DyPt5 are found to be present at 900 ◦ C. An example of X-ray diffraction obtained for the Dy3 Pt4 compound is shown in Fig. 4. It suggests that the phase Dy3 Pt4 still exists in the Fe–Pt–Dy ternary system, which is different from the phase Pr3 Pt4 that is unstable and decomposes into the two neighboring
Fig. 1. XRD pattern of the alloy corresponding to the composition 83.3 at.% Fe annealed at 900 ◦ C.
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compounds PrPt and PrPt2 with more than 1 at.% Fe [9]. The reason for this may be due to the fact that Dy is heavy rare earth, while Pr is light rare earth and the atomic radius of Dy is less than that of Pr. 3.2. Solid solubility
Fig. 2. The XRD patterns of Fe60 Pt5 Dy35 (top part) and Fe63 Pt2 Dy35 (bottom part) alloys annealed at 900 ◦ C.
At 900 ◦ C, by means of X-ray diffraction, differential thermal analysis, scanning electron microscopy and energy dispersion spectroscopy techniques, we have observed that the maximum solid solubility of Pt in Fe2 Dy and ␣-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively; the maximum solid solubility of Dy in ␣-(Fe, Pt), ␥-(Fe, Pt), FePt, FePt3 and (Pt, Fe) (the solid solution of Fe in Pt) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively; the maximum solid solubility of Fe in DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt is below 1 at.% Fe. 3.3. Isothermal section at 900 ◦ C By comparing and analyzing the X-ray diffraction patterns of 62 samples, together with scanning electron microscopy and energy dispersion spectroscopy on some of the selected samples, we have identified the phase components of each sample (in Table 2). According to these results, the solid state phase equilibria of Fe–Pt–Dy system at 900 ◦ C (Dy ≤ 75 at.%) was determined. The 900 ◦ C isothermal section, shown in Fig. 5, consists of 18 single-phase regions, 33 two-phase regions and 16 three-phase regions.
Table 2 Identification of phase for the ternary alloy
Fig. 3. SEM micrograph of Fe60 Pt5 Dy35 sample annealed at 900 ◦ C.
Fig. 4. Observed XRD pattern of Fe10 Pt50 Dy40 alloy annealed at 900 ◦ C.
Samples
Ternary alloys
Phase components
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
Fe35 Pt15 Dy50 Fe41 Pt15 Dy44 Fe58 Pt10 Dy32 Fe60 Pt10 Dy30 Fe63 Pt2 Dy35 Fe63 Pt5 Dy32 Fe70 Pt10 Dy20 Fe70 Pt15 Dy15 Fe92 Pt5 Dy3 Fe98 Pt1 Dy1 Fe50 Pt30 Dy20 Fe55 Pt30 Dy15 Fe60 Pt30 Dy10 Fe66 Pt31 Dy3 Fe56 Pt40 Dy4 Fe52 Pt44 Dy4 Fe10 Pt50 Dy40 Fe40 Pt51 Dy9 Fe44 Pt51 Dy5 Fe47 Pt51 Dy2 Fe40 Pt58 Dy2 Fe30 Pt67 Dy3 Fe23 Pt75 Dy2 Fe17 Pt80 Dy3 Fe6 Pt92 Dy2
Fe2 Dy + Dy3 Pt + Dy2 Pt Fe2 Dy + Dy5 Pt3 Fe23 Dy6 + Dy5 Pt3 Fe23 Dy6 + Dy5 Pt3 + Dy5 Pt4 Fe2 Dy Fe3 Dy + Fe2 Dy + Dy5 Pt3 Fe17 Dy2 + Dy5 Pt4 ␣-Fe + DyPt ␣-Fe + Dy3 Pt4 ␣-Fe ␣-Fe + Dy3 Pt4 + DyPt2 ␣-Fe + DyPt2 ␥-(Fe, Pt) + DyPt2 ␥-(Fe, Pt) + FePt + DyPt2 ␥-(Fe, Pt) + FePt + DyPt2 FePt + DyPt2 ␣-Fe + DyPt + Dy3 Pt4 FePt + DyPt2 FePt + DyPt2 + DyPt3 FePt + DyPt3 + FePt3 FePt + DyPt3 + FePt3 FePt3 + DyPt3 FePt3 + DyPt3 FePt3 + DyPt5 + Pt Pt + DyPt5
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the disparity is not clear and further detailed characterization is required. 4. Conclusion
Fig. 5. Isothermal section of the phase diagram of the Fe–Pt–Dy ternary system at 900 ◦ C.
Eighteen single-phase regions are ␣(␣-Fe), (␥-(Fe, Pt)), ␥(FePt), ␦(FePt3 ), (Pt), (DyPt5 ), (DyPt3 ), (DyPt2 ), (Dy3 Pt4 ), (DyPt), (Dy5 Pt4 ), (Dy5 Pt3 ), (Dy2 Pt), (Dy3 Pt), о(Fe2 Dy), (Fe3 Dy), (Fe23 Dy6 ) and (Fe17 Dy2 ). Thirty-three two-phase regions are ␣ + ,  + ␥, ␥ + ␦, ␦ + , + , + , + , + , + , + , + , + , + , + о, о + , о + , о + , + , + , + , + , + , + , + , + ␣, ␣ + , ␣ + , ␣ + ,  + , ␥ + , ␥ + , ␦ + and ␦ + . Sixteen three-phase regions are о + + , о + + , о + + , + + , + + , + + , + + , + + ␣, ␣ + + , ␣ + + , ␣ + + ,  + + ␥, ␥ + + , ␥ + + ␦, ␦ + + and ␦ + + . Compared with Fe–Pt–Pr system [9], it is observed in the 900 ◦ C isothermal section that the DyPt5 compound co-exists with the FePt3 instead of FePt in equilibrium condition, which is different from PrPt5 (CaCu5 structure type). The reason for this may be due to the fact that Dy (heavy rare earth) and Pr (light rare earth) have different Pauling and atomic radius, and the structure type of FePt3 (AuCu3 structure type) is different with that of FePt (AuCu structure type). The reason for
1. At 900 ◦ C, Dy3 Pt, Dy2 Pt, Dy5 Pt3 , Dy5 Pt4 , DyPt, Dy3 Pt4 , DyPt2 , DyPt3 and DyPt5 phases exist in Fe–Pt–Dy ternary system. The Dy3 Pt4 phase remains stable with the addition of Fe element. 2. The maximum solid solubility of Pt in Fe2 Dy and ␣-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively; the maximum solid solubility of Dy in ␣-(Fe, Pt), ␥-(Fe, Pt), FePt, FePt3 and (Pt, Fe) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively; the maximum solid solubility of Fe in DyPt5 , DyPt3 , DyPt2 , Dy3 Pt4 , DyPt, Dy5 Pt4 , Dy5 Pt3 , Dy2 Pt and Dy3 Pt is below 1 at.% Fe. 3. The 900 ◦ C isothermal sections of the phase diagram of the Fe–Pt–Dy ternary system (Dy ≤ 75 at.%) consist of 18 single-phase regions, 33 two-phase regions and 16 threephase regions. The existence of any new ternary compounds was not observed. Acknowledgement This work was supported by the National Natural Science Foundation of China (authorized number: 50261002). References [1] T.B. Massalski (Ed.), Binary Alloy Phase Diagrams, second ed., ASM International, Materials Park, OH, 1990. [2] W. Claus, G. Nolze, Federal Institute for Materials Research and Testing Rudower Chaussee, Berlin, 2000. [3] P. Villars, L.D. Calvert, Pearson’s Handbook of Crystallographic Data for Intermetallic Phases, ASM International, Materials Park, OH, 1991. [4] Powder Diffraction File, International Center for Diffraction Data [M], Pennsylvania, 1993. [5] D. Maccio, F. Rosalbino, A. Saccone, S. Delfino, J. Alloys Compd. 391 (2005) 60–66. [6] B. Erdmann, C. Keller, J. Solid State Chem. 7 (1973) 40–48. [7] W. Bronger, J. Less-Common Met. 12 (1) (1967) 63–68. [8] K. Nassau, L.V. Cherry, W.E. Wallace, Phys. Chem. Solids 16 (1960) 123–130. [9] R. Jing, G. Zhengfei, J. Alloys Compd. 394 (2005) 211–214.