Martensitic to austenite phase transition in ZrPd
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Martensitic to austenite phase transition in ZrPd Ram Sewak1,2
· Chandi Charan Dey1,2
© Springer Nature Switzerland AG 2019
Abstract The equiatomic alloy ZrPd has been studied by perturbed angular correlation (PAC) spectroscopy in the temperature range 298-973 K to observe the martensitic to austenite phase transformation. In ZrPd, a predominant component (∼56%) found at room temperature with values of quadrupole frequency ωQ = 39.5(5) Mrad/s, asymmetry parameter η = 0.44(2) and frequency distribution width δ = 10(2)% is tentatively assigned to the monoclinic martensitic phase of ZrPd. At 373 K, a small component (∼7%) with values of ωQ = 26(3) Mrad/s, η = 0 appears which enhances with temperature at the expense of the martensitic phase and is found to be ∼35% at 973 K. This new component, probably, arises due to structural transition from monoclinic martensitic to cubic austenite phase, a phase transformation reported to occur around 830 K in previous work. Keywords Intermetallic alloy ZrPd · Martensitic transformation · Perturbed angular correlation · BaF2 -BaF2 set up · X-ray diffraction
1 Introduction Equiatomic intermetallic alloys consisting of Ti, Zr, Hf in one group and Ni, Pd and Pt in the other group exhibit the martensitic transformation, leading to a characteristic of shape memory alloys. The well known shape memory alloy TiNi known as “nitinol” has a martensitic transformation (MT) below 373 K but for applications in the fields of aeronautics or space it requires high MT temperature. The alloys ZrPd and HfPd, on the other hand, are known to have high MT temperature [1–3]. It was reported by Nishiura et al. [2] that equiatomic ZrPd has martensitic phase transformation at 830 K. In ZrPd alloy, three crystallographic phases The present work is supported by the Department of Atomic Energy, Goverment of India through the Grant no. 12-R&D-SIN-5.02-0102. This article is part of the Topical Collection on Proceedings of the International Conference on Hyperfine Interactions and their Applications (HYPERFINE 2019), Goa, India, 10-15 February 2019 Edited by S. N. Mishra, P. L. Paulose and R. Palit Ram Sewak
[email protected] 1
Saha Institute of Nuclear Physics, Kolkata-700064, India
2
Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India
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were reported by Bendersky et al. [1]. These are: a high temperature cubic B2 type phase at 800 ◦ C, an orthorhombic CrB type phase (space group Cmcm) formed by martensitic transformation from the cubic B2 phase at 400 ◦ C and a monoclinic phase (space group Cm) at room temperature. It was also reported [1] that monoclinic to orthorhombic phase transition occurs reversibly around 200 ◦ C. The ZrPd alloy was studied also by Waterstrat et al. [4]. From their studies, two new phases viz. Zr3 Pd4 and Zr9 Pd11 were reported. From previous measurements in ZrPd [2, 5], it was found that ZrPd compound transforms to Zr13 Pd12 and Zr9 Pd11 compounds by a eutectoid reaction at about 1028 K. The lattice paramete
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