Anelasticity of the martensitic phase of Ni55Fe18Ga27 single crystals in hyperstabilized and nonstabilized states

• Published in: Journal of alloys and compounds Vol. 908; p. 164528
• Main Authors: Sapozhnikov, K., Kustov, B., Krymov, V., Nikolaev, V.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05-07-2022; Elsevier BV
• Subjects: Acoustic properties; Anelasticity; Crystal defects; Divacancies; Elastic properties; Heat treatment; Internal friction; Modulus of elasticity; Ni-Fe-Ga alloy; Pinning; Point defects; Single crystals; Temperature dependence; Twin boundaries; Ultrasonics; Vacancies; Ni-Fe-Ga alloy; Twin boundaries; Acoustic properties; Internal friction; Vacancies; Ultrasonics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.164528

Apparent elastic and anelastic properties of the martensitic phase of Ni55Fe18Ga27 single crystals have been studied after different heat treatments over wide ranges of temperatures (13–370 K) and strain amplitudes (5 × 10-8–10-5) at frequencies near 100 kHz. These properties depend crucially on the heat treatment because of strong pinning of twin boundaries by quenched-in point defects. Two stages are revealed in the temperature dependence of the effective Young’s modulus and anelastic properties of the alloy that can be associated with pinning/depinning of twin boundaries by/from different types of point defects, most likely vacancies and divacancies. Experimental data evidence that diffusion of the vacancy-type defects in the temperature range under study is predominantly defect-assisted, enhanced by twin boundaries.
•Thermal treatment radically affects anelastic properties of a Ni-Fe-Ga alloy.•Interaction of twin boundaries with point defects in Ni-Fe-Ga is studied.•Twin boundaries in Ni-Fe-Ga trap vacancies and divacancies.•Divacancies are responsible for hyperstabilization of Ni-Fe-Ga by quenching.•Vacancy diffusion in Ni-Fe-Ga is accelerated by twin boundaries.