The strengthening effect of Al 3Ti in ultrafine grained Al-Al 3Ti alloys

Abstract

Aluminum alloys prepared by mechanical alloying (MA) usually contain significant amount of ultrafine carbide and oxide dispersoids, which play vital roles in obtaining the fine grains and high strength in these alloys. The stiffness and strength of such alloys can be further improved by adding aluminum-transition metal intermetallic phases. As compared to most aluminum-rich intermetallic phases, Al{sub 3}Ti has many attractive properties. The unique microstructure of the MA Al-Al{sub 3}Ti alloys, i.e., submicron grain size and uniform dispersion of fine carbides and oxides, is quite common for alloys produced by the MA process. According to the characteristics of the microstructure, the MA Al-Al{sub 3}Ti alloy may be considered as a fine Al-Al{sub 3}Ti two-phase composite, in which the aluminum matrix is further strengthened by the fine dispersoids of carbide and oxide. Such a two-phase composite with submicron sized grains for both phases cannot be easily obtained by other means. Therefore, it is worthwhile to study the strengthening mechanisms in the MA Al-Al{sub 3}Ti alloys, especially the role of the submicron sized reinforcements, Al{sub 3}Ti.