Zhang Haoyu, Wang Chuan, Zhang Siqian, Zhou Ge, Chen Lijia
School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China.
College of Light Industry, Liaoning University, Shenyang 110036, China.
Materials (Basel). 2018 Nov 15;11(11):2283. doi: 10.3390/ma11112283.
Evolution of secondary α phase during aging treatment of a novel near β titanium alloy Ti-6Mo-5V-3Al-2Fe(wt.%) was studied by OM, SEM, and TEM. Results indicated that size and distribution of secondary α phase were strongly affected by aging temperature and time. Athermal ω phase formed after super-transus solution treatment followed by water quenching, and promoted nucleation of needle-like intragranular α in subsequent aging process. When aged at 480 °C, fine scaled intragranular α with small inter-particle spacing precipitated within β grains and high ultimate tensile strength above 1500 MPa was achieved. When the aging temperature increased, the size and inter-particle spacing of intragranular α increased and made the strength reduce, but the ductility got improved. When aging temperature reached as high as 600 °C, ω phase disappeared and intragranular α coarsened obviously, resulting in serious decrease of strength. While mutually parallel Widmanstätten α laths formed at the vicinity of β grain boundaries and grew into the internal area of β grains, and significant improvement of ductility was achieved. As the aging time increased from 4 h to 16 h at 600 °C, the intragranular α grew slightly and brought about minor change of mechanical properties.
通过光学显微镜（OM）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究了新型近β钛合金Ti-6Mo-5V-3Al-2Fe（质量分数）在时效处理过程中次生α相的演变。结果表明，次生α相的尺寸和分布受时效温度和时间的强烈影响。超α相固溶处理后水淬形成了无热ω相，并在随后的时效过程中促进了针状晶内α相的形核。在480℃时效时，β晶粒内析出了颗粒间距小的细片状晶内α相，获得了高于1500MPa的高抗拉强度。当时效温度升高时，晶内α相的尺寸和颗粒间距增大，强度降低，但塑性提高。当时效温度高达600℃时，ω相消失，晶内α相明显粗化，导致强度严重下降。而在β晶界附近形成了相互平行的魏氏α板条，并向β晶粒内部生长，塑性得到显著提高。在600℃时效时，当时效时间从4h增加到16h，晶内α相略有长大，力学性能变化较小。
