Effect of ageing treatment on the transformation behaviour of Ti–50.9 at.% Ni alloy

✍ Scribed by Yufeng Zheng; Fei Jiang; Li Li; Hong Yang; Yinong Liu

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 863 KB
• Volume: 56
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2007.10.020

✦ Synopsis

This study investigated the effect of ageing on the transformation behaviour of a Ti-50.9 at.% Ni alloy. Ageing at below 573 K was found to suppress the original A M M transformation. This phenomenon has not been recognized in the literature. The effect is ascribed to the lowering of B2 ordering of the matrix caused by the formation of GP zones as a pre-phenomenon for precipitation. Ageing at between 573 and 813 K resulted in complex multiple-stream transformations. These complex transformation behaviours are attributed to long-range heterogeneity of precipitation structure between grain boundaries and grain interior, and short-range heterogeneity caused by partial dissolution of coherent precipitates and formation of incoherent precipitates. Ageing at above 833 K led to a single-stage A M M transformation, which indicates total dissolution of coherent Ti 3 Ni 4 .