Abstract
The closed powder metallurgy processing system for the production and consolidation of rapidly soldified powders has been developed in Institute for Materials Research, Tohoku University. The sequent steps can be carried out in a vacuum or argon gas atmosphere containing oxygen and moisture of 0.5 ppm without exposing the powder to air, The superiorities of the closed process were: 1) improvement of the strength and ductility of compacts, 2) reduction of the working degree of consolidation and enlargement of the dimensions of compacts, 3) abbreviation of the degassing process or lowering of the degassing temperature, 4) reduction of the thermal history, 5) widening of the consolidation conditions, 6) safety production and consolidation of reactive powders. The synthesize of nanocrystalline aluminum alloys by crystallization of amorphous phase was exemplified as developments of advanced materials using the closed P/M processing system. The nanocrystalline Al-Ni-Ln-(Co, Ti, Zr) (Ln: lantanide metal) alloys had high strength at room and elevated temperatures, high Young's modulus, high wear resistance, low thermal expansion etc.
