High-temperature tensile and creep properties of TiB-reinforced Ti6Al4V composite fabricated by laser powder bed fusion

作者：Zhou, Zhiguang; Liu, Yunzhong^*; Liu, Xiaohui; Wu, Lidong

来源：Materials Characterization, 2023, 200: 112859.

DOI：10.1016/j.matchar.2023.112859

• Ti6Al4V-TiB composite
• Laser powder bed fusion
• High-temperature
• Creep

Titanium matrix composites prepared by laser powder bed fusion (LPBF) have received extensive attention, but the research on their high-temperature performance was extremely limited. This work investigated the high -temperature tensile and creep properties of an LPBF-fabricated TiB-reinforced Ti6Al4V composite. The results showed that the as-built Ti6Al4V-TiB composite exhibited higher tensile strength and creep resistance than the as-built Ti6Al4V alloy under the given experimental conditions. Three heat-treated microstructures (fully lamellar, bilamellar, and bimodal) were constructed in Ti6Al4V-TiB composite and their creep behaviors were preliminarily compared, and further creep investigations were carried out on the composite sample with a bimodal microstructure. Microstructural evolution was observed before and after the creep test. The dislocation climb process in creep promoted the rearrangement of dislocations, leading to the occurrence of dislocation walls and cellular substructures, from which the subgrains originate. A large number of dislocations accumulated around the TiB whiskers, which indicates that TiB whiskers can effectively pin dislocations and therefore enhance the creep resistance. For the bimodal Ti6Al4V-TiB composite, the massively increased alpha p/beta t phase interface was the main source of improving creep resistance, and plastic deformation preferentially occurred in the beta t region.