Preparation of TZM alloy by aluminothermic smelting and its characterization

Molybdenum based alloy having a nominal composition Mo-0.5Ti-0.08Zr-0.02C (wt.%) popularly known as TZM alloy is of immense interest amongst scientists worldwide for development in view of its excellent combination of metallurgical properties suitable for high temperature applications. In the present investigation, attempts were made to prepare this alloy by a non-conventional non-furnace process. The process essentially involves the use of cheap, indigenously available oxides of molybdenum, titanium and zirconium for their co-reduction with large excess of aluminium in presence of requisite amount of carbon in a simple experimental set-up. The charge composition was judiciously adjusted to achieve maximum alloy yield by utilizing the heat of the chemical reactions effectively. A typical charge constituting Al 10 wt.% over stoichiometric amount, MoO2 stoichiometric amount, ZrO2, TiO2 two and five times the requisite amount, respectively and C 50% excess the required amount with an overall specific heat of the charge as 680 kcal kg(-1) has resulted in an alloy yield of 92%. The as-reduced alloy after consolidation by remelting has exhibited the composition nearly matching the targeted composition. The alloy was further characterized with respect to composition, phases, microstructure and properties such as hardness, rolling, oxidation and coating to evaluate its suitability for high temperature applications. (c) 2004 Elsevier B.V. All rights reserved.