Effect of alloying elements Ti, Zr on the property and microstructure of molybdenum

Mo-Zr and Mo-Ti alloy were fabricated by adding alloying element Zr, Ti in molybdenum via powder metallurgy process. The effect of Zr, Ti alloying elements on the tensile strength and microstructure of molybdenum are investigated. Two types of alloying additives are used: one is elemental powder of Zr or Ti; the other is their respective hydride powders, TiH2 or ZrH2. The experimental results show that the formed Mo-Zr, Mo-Ti alloy possess much higher mechanical properties than pure sintered molybdenum. The tensile strength of Mo-Zr alloy is more affected by adding elemental Zr powder than ZrH2 powder, the optimal tensile strength is obtained with addition of 0.1 wt% Zr, most of Zr forms Zr-oxide existed both inside the grain and at the grain boundaries, while very little Zr diffuses into the Mo matrix. Meanwhile, for Mo-Ti alloy, the tensile strength is more influenced by addition of TiH2 powder than elemental Ti powder, the tensile strength is optimized at the content of 0.8 wt% TiH2, some Ti diffuses into molybdenum and forms Mo-Ti solid solution and some forms as MoxTiyOz oxide particles uniformly distributed at the grain boundaries. (C) 2008 Elsevier Ltd. All rights reserved.