PRODUCTION OF ALUMINUM ALLOY HAVING HIGH STRENGTH AND HIGH TOUGHNESS AND ALLOY STOCK

摘要

PURPOSE:To produce an Al alloy having high strength and high toughness by subjecting an Al alloy stock having a specific single-phase structure containing specific amounts of Y, Fe, etc., to heat treatment and providing a specific dual-phase structure. CONSTITUTION:An alloy stock having a composition represented by chemical formula AlaTbXc (where T means one or more elements among Y, La, Ce, Mm, and Ca, X means one or more elements among Fe, Co and Ni and, when Y alone is selected X is either or both of Co and Ni, 85=a=97, 1=b=10, and 2=c=15) and also having a primary structure in which the volume fraction Vf of a single-phase structure having fcc structure and consisting of crystalline grains of 30nm grain diameter comprises =90% is prepared. Heat treatment is applied to this alloy stock at a temp. in the region of (decomposition temp. of the single-phase structure)+ or -100 deg.C to decompose the single-phase structure, by which a secondary structure having a dual-phase structure where intermetallic compounds are uniformly dispersed in a matrix consisting of crystals having =400nm grain diameter formed. By this method, the Al alloy improved in strength at high temp. and toughness as well as in strength at ordinary temp. can be obtained.