Sintering experiments have been conducted on Cu-4wt%Al and Fe-4wt% Al compacts. Quenching after heating allows the examination of the behavior of transient liquid phase, the intermetallic compound formation and homogenization processes of sintering compacts. The examinations included are electron probe micro-analysis, scanning electron microscopy, differential thermal analysis and dilatometry. In Cu-4wt% Al system, the liquid phase, formed by eutectic reaction, has so high a tendency of forming Cu-Al intermetallic compounds that it is not able to flow due to its short life time. The other liquid phase, formed by the peritectic reaction of θ and $η_1$ phase, flows to form another phase within a few minutes when the green density is low, but the flow is difficult when the green density is high. This flow behavior of liquid phase occurred during heating may be closely related to the chemical potential of liquid and the pore channel size in the compact. The compacts accompanied by this flow of Al rich liquid phase have been homogenized during heating to 975℃. During heating to 1030℃, micro-pore group is formed around Alrich phase because of Kirkendall effect.
In Fe-Al system, most of the Al transformed into intermetallic compounds during heating to the eutectic temperature at 15℃/min. A small amount of liquid phase formed at that temperature does not flow and immediately transformed into intermetallic compounds. The formation of intermetallic compounds results in volumetric expansion and lead to stress generation which is responsible for the creation of crack observed in Fe matrix of the compact. The sudden and large expansion around eutectic temperature may be attributed to these phenomena and the amount of swelling depends on the amount of aluminum added.
