Effect of solidification rate on microstructure and crystal orientation of ferromagnetic shape memory alloys Co–Ni–Al

✍ Scribed by J. Liu; H.X. Zheng; J.G. Li

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 871 KB
• Volume: 438-440
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2006.02.142

✦ Synopsis

Effect of solidification rate on the solidified microstructure and crystal orientation based on a new type ferromagnetic shape memory Co-Ni-Al alloys have been studied by the liquid metal cooling directional solidification. The results show that at the lower rate of 5 m/s for the Co 32 Ni 40 Al 28 alloys, worm-like ␥ phase precipitated in martensite matrix and faceted ␥ particles were introduced under the rate of 10 m/s. For a rather faster growth rate of 150 m/s, interdendritic ␤ + ␥ eutectic lamella appears after the dendritic ␤ formed. The single austenite phase was observed in the Co 38 Ni 34 Al 28 alloy at the rate of 5 m/s. At the same time, the preferred orientations changed with the variation of the solidification conditions. It is found that 1 1 1 oriented martensite crystal can be obtained in the Co 32 Ni 40 Al 28 alloy at the rate of 5 m/s, while 1 1 0 and 1 0 0 orientations become stronger at the rate of 10 m/s. But the preferred orientation degree at 150 m/s is very poor. The Co 38 Ni 34 Al 28 rod with 1 1 0 oriented austenite can be prepared at the rate of 5 m/s.