Metal injection molding of high-performance Ti composite using hydride-dehydride (HDH) powder

Abstract

Aiming at solving the interstitial oxygen contamination for titanium (Ti) parts fabricated by metal injection molding (MIM) technology, we innovatively introduced LaB6 oxygen scavenger to eliminate its adverse effect and produce a high-performance Ti material using inexpensive hydride-dehydride (HDH) Ti powders. Rheological behavior of feedstocks, decomposition behavior of binders, as-sintered microstructure and mechanical properties were systematically studied. The viscosity of feedstock F2 containing LaB6 powder meets the requirement of injection molding operation. The as-sintered 0.5 wt% LaB6/Ti composite has homogenous and fine microstructure with the average grain size of 65.6 μm. The in-situ TiB and oxygen-containing (La2O3 and La-Cl-O) reinforcements are formed by the reaction of LaB6 and Ti matrix, which are uniformly distributed in the composite. The generated TiC particle and Ti matrix exist an orientation relation of (111¯)TiC||(011¯0)Ti and [101]TiC||[0001¯]Ti. The LaB6/Ti composite possesses excellent mechanical properties, with the ultimate tensile strength of 632 MPa, yield strength of 548 MPa and elongation of 15 %. Attributed to the oxygen scavenger of LaB6, the elongation of the composite is greatly increased by 163 % compared with pure Ti. This work provides a valuable guidance for the development of low-cost and high-performance Ti parts by MIM technology.