Antiphase boundary-like structure in α′′ martensite of TC21 titanium alloy
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Sciences and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Beijing Institute of Aeronautical Materials, Beijing 100095, China)
2. Key Laboratory of Nonferrous Metal Materials Sciences and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Beijing Institute of Aeronautical Materials, Beijing 100095, China)
Abstract: The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α′′ occurs upon quenching after solution treatment between 960-1000 °C. The antiphase boundary (APB)-like structure was observed clearly in the α′′ martensite plates. The APB-like contrasts exist along the (001) and (020) planes of α′′ martensite. This APB-like structure of α′′ martensite was identified as a kind of stacking fault with an APB-like morphology induced by martensitic transformation and not by order/disorder transition. During martensitic transformation, martensitic domains nucleate and grow, eventually encounter each other, resulting in the formation of the APB-like contrast.
Key words: titanium alloy; martensitic transformation; antiphase boundary (APB); crystal structure