Abstract
It has been found that the sintered MIM Ti-6Al-4V alloy compacts were strengthened by addition of fine Mo powder because of the microstructural modification. In this study, the metal injection molding process has been applied to strengthen Ti-6Al-4V compacts by addition of Fe or Cr powders, which are the same beta stabilizing elements as Mo and are more cost effective powders as compared to Mo powder. The effect of Fe or Cr contents and sintering conditions on the mechanical properties, oxygen content and microstructures of the sintered compacts were mainly investigated. The microstructures of sintered compacts were consisted of acicular alpha phase and intergranular beta phase, and the acicular alpha phase showed fine with increasing Cr content. The tensile strength of sintered compacts was increased with increasing Fe or Cr contents, and the effect of Fe addition for strengthening the sintered compacts was larger than Cr or Mo addition. Eventually, the tensile strength of sintered compacts added 2 mass% of Fe was improved to be 1010 MPa with 11.2 % of elongation, and the compacts added 4 mass% of Cr showed the excellent tensile strength of 1040 MPa with 16.1 % of elongation.
