Phase Transformation and Shape Memory Effect of Ti(Pt, Ir)

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 43; no. 8; pp. 2901 - 2911
• Main Authors: Yamabe-Mitarai, Yoko, Hara, Toru, Miura, Seiji, Hosoda, Hideki
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.08.2012; Springer; Springer Nature B.V
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Diffraction; Exact sciences and technology; High temperature; Materials Science; Metallic Materials; Metals. Metallurgy; Nanotechnology; Phase transitions; Strain; Structural Materials; Surfaces and Interfaces; Symposium: Physical and Mechanical Metallurgy of Shape Memory Alloys for Actuator Applications; Thin Films; Shape Memory Effect; Martensitic Transformation Temperature; Shape Memory; Strain Recovery; TiNi; Geometrical shape; Phase transformation; Martensitic transformation; Shape memory alloy; Shape memory effect
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-011-0954-y

The martensitic transformation and shape memory effect of Ti 50 (Pt, Ir) 50 with 5–37.5 at. pct Ir were investigated using differential thermal analysis (DTA), high-temperature X-ray diffraction (HT-XRD), and compression tests. The austenite finish temperature, A f , increased with increasing Ir content from 1331 K (1058 °C) in Ti-50 at. pct Pt to 1491 K (1218 °C) in Ti-12.5Pt-37.5Ir. The structure of the parent and martensite phases was identified as B2 and B19 in all tested alloys. A large strain recovery rate was obtained in Ti 50 (Pt, Ir) 50 with 10 to 30 at. pct Ir. The highest shape recovery ratio was 57 pct in Ti-25Pt-25Ir after deformation at 1123 K (850 °C), followed by heating to above A f . Using HT-XRD, the dependence of lattice parameter change on Ir content and temperature was investigated. The volume change during phase transformation from B2 to B19 was estimated using the lattice parameter of the B2 and B19 phases. Strain recovery is discussed along with volume change and lattice parameter change.