Rare Earth Element: Is it a Necessity for PM Ti Alloys?

Abstract

To lower the cost, Ti alloys fabricated by elemental powder metallurgy have been widely studied. High contents of oxygen and residual porosities are usually inevitable in as-sintered Ti alloys. Thus, rare earth elements are added to PM Ti alloys for scavenging of oxygen, increasing sintered density and strengthening the matrix. This paper reviews recent studies on the effects of rare earth elements (La and Y) on the densification behaviours, mechanical properties and high temperature oxidation resistance of PM Ti alloys. The improvement of room temperature ductility of PM Ti alloys through the addition of rare earth elements has been extensively confirmed. However, other benefits from rare earth additions depend largely on alloy compositions, processing parameters and environmental conditions.