Evolution of Secondary ? Phase during Aging Treatment in Novel near ? Ti-6Mo-5V-3Al-2Fe Alloy.

ABSTRACT: Evolution of secondary ? phase during aging treatment of a novel near ? titanium alloy Ti-6Mo-5V-3Al-2Fe(wt.%) was studied by OM, SEM, and TEM. Results indicated that size and distribution of secondary ? phase were strongly affected by aging temperature and time. Athermal ? phase formed after super-transus solution treatment followed by water quenching, and promoted nucleation of needle-like intragranular ? in subsequent aging process. When aged at 480 °C, fine scaled intragranular ? with small inter-particle spacing precipitated within ? grains and high ultimate tensile strength above 1500 MPa was achieved. When the aging temperature increased, the size and inter-particle spacing of intragranular ? increased and made the strength reduce, but the ductility got improved. When aging temperature reached as high as 600 °C, ? phase disappeared and intragranular ? coarsened obviously, resulting in serious decrease of strength. While mutually parallel Widmanstätten ? laths formed at the vicinity of ? grain boundaries and grew into the internal area of ? grains, and significant improvement of ductility was achieved. As the aging time increased from 4 h to 16 h at 600 °C, the intragranular ? grew slightly and brought about minor change of mechanical properties.

SUBMITTER: Zhang H 

PROVIDER: S-EPMC6267200 | biostudies-other | 2018 Nov

REPOSITORIES: biostudies-other