Chloride Impurities in Titanium Powder Metallurgy-A Review

Chloride impurities in titanium powder are a critical and long-standing barrier to the manufacture of low cost powder metallurgy components. A brief review with 40 references is presented in which the two most severe problems caused by chlorides in powder metallurgy are discussed. The volatile behaviour of these impurities at high temperature causes macroporosity during sintering which impairs mechanical properties. During welding, the presence of chlorides and molten material causes severe defects and complications. The origins of chlorides and the existing mitigation strategies are also covered. In general, an effective solution to the problem remains elusive. However the impurity can be tolerated in certain cases where weldability and fatigue properties are not critical.