Abstract
The structural change and some incidental properties of Al-Cr (up to 3 wt%) alloys by rapid solidification at varying cooling rates 102 to 103°C/sec were investigated. The results obtained are as follows: (1) It is shown that the supersaturated solid solutions can be formed by rapid solidification and the minimum cooling rate to dissolve solute Cr supersaturatedly in pure Al is more than about 600°C/sec for 2 wt%Cr and about 1000°C/sec for 3 wt%Cr, respectively. (2) The microstructure of these solid solutions are composed of the dendritic cell structure of the primarily crystallized α phase and appearance of CrAl7, which has to crystallize primarily in an equilibrium condition, is obstructed. (3) The decomposition temperature of the supersaturated solid solutions of Al-2 wt%Cr alloys is 250°∼300°C and is lower by 100°C than that of Al-Mn system. (4) No precipitation hardening cannot be recognized by decomposition of these supersaturated solid solutions.
