Study of microstructure and compressive strength of a novel Ti-0.75Al-9.5V alloys manufactured by laser deposition melting

Abstract

A novel Ti-0.75Al-9.5 V alloy is designed based on the typical Ti-6Al-4V alloy and prepared by laser melting deposition in this study. The microstructure, texture, and properties of the different scanning and building planes of the LMDed samples under a serpentine reciprocating scanning strategy are characterized and tested. It is found that the more rapid cooling rate on the building planes leads to a partial morphology transformation of the α phase from the original rod-like shape to a needle-like shape. Furthermore, different maximum thermal stress gradients result in the formation of (110)β texture and (001)β texture on different building planes while The (110)β // (0001)α crystallographic orientation relation leads to the formation of the (21¯1¯0)α texture on both two building planes during solid-phase transformation. The texture evolution on two different building planes also affects corresponding surface slip and mechanical properties. The (001)β texture leads to parallel surface slip tracks on its building plane. The strong (110)β and (21¯1¯0)α textures increase the Vickers hardness from 348.6 ± 2.6 to 371.5 ± 2.7 HV and the compressive yield strength from 1188.0 ± 1.6 to 1276.5 ± 7.3 MPa but suppress the plastic strain from 16.7 ± 0.9% to 12.6 ± 1.0%. All the samples have their compressive fractural strength nearing 1730 MPa, which is higher than that of the reported LMDed Ti-6Al-4V alloy (1690 MPa).