Abstract: A tool for friction stir welding or forming is provided. The tool comprises a shoulder portion (40b) and optionally a pin portion (5Ob)l the shoulder portion (40b) comprised of at least 60% by weight and up to 100% by weight of tungsten, molybdenum, tantalum, niobium or hafnium, the balance being alloying materials, if used. The tool has at least one surface treatment or coating. Articles welded by the tools are also provided.

Abstract: The present invention provides a molybdenum alloy which suitably comprises in the range of from 0.2 to 1.0% by weight of an oxide of a specified metal prepared by adding a salt of the metal in dissolved form to molybdenum and/or a molybdenum oxide or a mixture of different molybdenum components, reducing this mixture at a temperature of up to 1150.degree. C. using hydrogen, pressing the reduced metal without the addition of a binder suitably under a pressure of from 150 to 300 mPA, and sintering the product at a temperature in the range of from 1750.degree. to 2200.degree. C. It is preferable to add salts of zirconium to the molybdenum oxide.