Effect of varying α phase fraction on the mechanical properties and deformation mechanisms in a metastable β-ZrTiAlV alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2020-01, Vol.772, p.138784, Article 138784
• Main Authors: Liao, Zhongni, Luan, Baifeng, Zhang, Xinyu, Liu, Riping, Murty, Korukonda L., Liu, Qing
• Format: Article
• Language: English
• Subjects: Beta phase; Deformation effects; Deformation mechanisms; Elongation; Evolution; Hardening rate; Kink bands; Martensite; Mechanical properties; Mechanical twinning; Metastable β-Zr alloy; Work hardening; Zirconium base alloys; α phase fraction
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2019.138784

We systematically investigated the effects of varying α phase fraction on the mechanical properties and deformation mechanisms in a metastable β-51.1Zr-40.2Ti-4.5Al-4.2V (wt. %) alloy containing mixed α + β phase. Various heat treatments from single β phase regime to dual α+β phase regime were imposed in order to alter the volume fraction of α phase. The results show that the triggering stress increases and the total elongation decreases with the increasing α phase fraction. As the α phase fraction increases, the work hardening rate curve changes from an obvious parabolic evolution to a monotonically decreasing evolution and the work hardening effect is gradually reduced. Co-existence deformation mechanisms of kink bands, deformation-induced α′ martensite and {101‾1}α′ mechanical twinning were detected in low α phase fraction samples but not in high α phase fraction sample. In intermediate α phase fraction sample, only deformation-induced α′ martensite was activated. For the first time, the effects of α phase fraction on the deformation-induced α′ martensite, {101‾1}α′ mechanical twinning and kink bands were observed in metastable β-Zr alloy. These effects of varying α phase fraction on the mechanical properties and deformation mechanisms are discussed based on the β stability and the β domain size.