Study of Ni–Mn–Ga–Cu as single-phase wide-hysteresis shape memory alloys

✍ Scribed by Yingying Li; Jingmin Wang; Chengbao Jiang

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 1013 KB
• Volume: 528
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2011.05.060

✦ Synopsis

Ni 50 Mn 25 Ga 25-x Cu x (x = 3-10) alloys were studied as single-phase wide-hysteresis shape memory alloys, with the microstructure, martensitic transformation temperatures and hysteresis, mechanical properties, and shape memory behaviors. Single phase of martensite with tetragonal structure was detected for x < 8, and dual phase containing martensite and the precipitated phase was observed for 8 < x ≤ 10. The martensitic transformation start temperature M s was linearly increased from 477 K for x = 5 to 673 K for x = 8, then remained constant for x > 9. Simultaneously, the transformation hysteresis A s -M s , between the austenitic start and the martensitic start temperatures, was monotonically expanded from 6.6 K for x = 5 to 40 K for x = 8. The ductility of Ni-Mn-Ga alloys was effectively improved by Cu addition via strengthening the grain boundaries. Shape memory effect of 4.4% was obtained in Ni 50 Mn 25 Ga 17 Cu 8 polycrystal. The wide transformation hysteresis, the achieved shape memory effect and the improved ductility indicate Ni-Mn-Ga-Cu alloys a promising candidate for single-phase wide-hysteresis shape memory alloys.