Age hardening behavior and precipitation structures were investigated for ribbons mainly of both an Al-1.8%Cr-1.7%Zr alloy and the alloy with the further additional element of Si, which were prepared by a rapid solidification method using a single roll. Then, the role of Cr or Si in the precipitation hardening process has been examined.
As a result, age hardening took place more remarkably in the Al-1.8%Cr-1.7%Zr alloy than that in a Al-1.7%Zr binary alloy. It is condidered that this is caused by the precipitation of fine and spherical particles of the metastable Al
3Zr phase with the Ll
2 structure, which has been made possible because the additional element of Cr retards the precipitation with the grain boundary reaction. By the addition of Si, together with Cr, to the Al-1.7%Zr alloy, the precipitation of the fine and spherical particles of the metastable phase has been accelerated. Thus, the addition of Si results in reaching higher values of the peak hardness.
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