A laser additive manufactured metastable Ti-10V-2Fe-3Al β-titanium alloy: Microstructure, mechanical properties, and deformation mechanisms

Abstract

In the present work, the deformation mechanism is investigated by tailoring the microstructure of a laser powder bed fusion (L-PBF) processed β-type Ti-10V-2Fe-3Al (Ti1023) alloy. The microstructure analysis shows columnar β grains with <001>//BD texture. The α phase appeared lath morphology after using laser power of 160 W and presented fine and intersected morphology at 200 W, and the shape of ω clusters transformed from bulk to intersected acicular with increasing laser power. The Ti1023 alloy exhibits excellent mechanical properties with a total elongation of 18 % and high yield strength above 828 MPa. The existence of α″ phase as well as {332}<113> and {112}<111> deformed twins were found in fractured microstructure at 160W, confirming the multiple deformation mechanisms consisting of dislocation slip, transformation-induced plasticity (TRIP), and twinning-induced plasticity (TWIP). By increasing the laser power, the deformation mechanisms are limited to dislocation slip. At last, the finite element analysis of the temperature and temperature gradient change reveals the underlying mechanism for microstructure evolution based on thermal history. This study provides a pathway to regulate L-PBF Ti1023 strengthening and work-hardening behavior by controlling the process parameters during the fabrication of the material.