초탄성 티타늄 합금의 인장 변형거동 고찰

• Published in: 대한금속·재료학회지, 58(3) Vol. 58; no. 3; pp. 162 - 168
• Main Authors: 정혜진, Hye-jin Jeong, 르우비엣띠엔, Viet Tien Luu, 정용하, Yong-ha Jeong, 홍성태, Sung-tae Hong, 한흥남, Heung Nam Han
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.03.2020; 대한금속·재료학회
• Subjects: dislocation slip; stress-induced martensitic transformation; superelastic titanium alloy; twinning; 재료공학
• ISSN: 1738-8228; 2288-8241

A superelastic titanium alloy was subjected to uniaxial tensile deformation at room temperature. The microstructural evolution and deformation mechanisms of the superelastic titanium alloy were investigated by electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). Multiple deformation mechanisms including stress-induced martensitic transformation (SIMT), dislocation slip, {332} and {112} mechanical twinning were identified with the increase in uniaxial strain. In the early stage of deformation, a SIMT from the bcc beta phase to orthorhombic martensite phase dominantly occurred. As the deformation proceeded, the phase fraction of the remained martensite which did not return to beta phase obviously increased due to dislocation slip and mechanical twinning. The kernel average misorientation (KAM) value obtained from EBSD data gradually increased with increasing the deformation, indicating that the dislocation evolution was produced by slip. This was well matched with the trend in the full width at half maximum (FWHM) value of the peak profile obtained from XRD data. In addition, the fraction of the {332} twin was lower than that of the {112} twin in the initial specimen. However, the {332} twin rapidly increased compared to the {112} twin as deformation increased. Therefore, it is confirmed that {332} twinning and dislocation slip were the dominant mechanisms during plastic deformation. (Received November 25, 2019; Accepted January 13, 2020)