Structural and Magnetic Properties of Magnetic Shape Memory Alloys on Ni-Mn-Co-In Self-standing Films

Abstract

Ni-Mn-In films containing cobalt were deposited on a poly-vinyl alcohol (PVA) substrate using a dual magnetron sputtering apparatus with Ni 45 Mn 40 In 15 and Co targets. The RF power for the Ni-Mn-In target was kept at 200 W, and the DC power for the cobalt target was 8 W. The thicknesses of the deposited films were 1 and 5 µm. After deposition, the films were annealed at 1123 K for 3.6 ks for 1 µm and 1023 K for 3.6 ks + 1173 K for 3.6 ks for 5 µm. The crystallinity of the films was affected by the heat treatment, and the films showed layered structures, such as 10M-and 14M-type structures. The martensitic transformation and magnetic phase transition influence each other, and both have a magnetic field dependence. In particular, the 5 µm film shows a metamagnetic phase transition with small transition temperature hysteresis. The magnetization experiments for the 5 µm film reveal a drastic magnetization change ΔM of 26 emu/g at 0.05 T and a martensitic transformation finish temperature change ΔM f of −8.5 K at 5 T.

High Field X-ray Diffraction Study for Ni46.4Mn38.8In12.8Co2.0 Metamagnetic Shape Memory Film

“…4 Mn 38.8 In 12.8 Co 2.0 . According to the reports about Ni-Co-Mn-In films [16,18], the transformation behavior was sensitive to the annealing condition, composition of Co, and so on. In this study, as described below, the transformation temperatures of Ni 46.4 Mn 38.8 In 12.8 Co 2.0 films are above room temperature (RT), which is suitable for observing the structural change by HF-XRD system at high temperature.…”

Metamagnetic Shape Memory Alloy Thin Plates Consolidated by Compression Shearing Method at Room Temperature for Thermal Energy Harvesting Device

“…Details of the sputtering process are given elsewhere. (18,19) The peeled film was crushed using a mortar to obtain MSMA powder for COSME-RT.…”

“…In previous research, it was confirmed that MSMA thin films show large changes in magnetization, a narrow temperature hysteresis, and a steep magnetic phase transition. (18,19) However, when mounted on an actuator, sufficient material strength and output for practical use cannot be obtained even with a film thickness of several microns. To obtain them, a film with a thickness of several tens of microns is required, but this is not achieved by simply increasing the sputtering time, which causes a new and fundamental problem that very fast erosion of the target occurs.…”

Effect of Electrolytic Polishing on Corrosion Fatigue Strength of TiNi Shape Memory Alloy

“…Shape memory materials (SMMs) are defined as substances that can revert to their original memorized shape upon an increase in temperature or other stimuli, such as magnetic field changes. (1,2) A shape memory alloy (SMA) is a typical SMM; in particular, a TiNi-series SMA (TiNi SMA) is the most popular SMA because of its excellent recovery stress and shape-recovering properties. The material has been used as an element in temperature sensors and in many types of actuators by using the shape memory effect, which is characterized by a shape-recoverable strain with heating.…”