Kinetic of the Intermetallic Phases Growing in the Al Alloy - Ni Composite

Abstract

This article describes the kinetic of intermetallic phases growth during annealing of Al alloy – Ni composite material. The composite was prepared by spark plasma sintering processing (SPS) from gas atomized AlCr6Fe2Si1 with 5 wt. % of Ni. The composite material is stable at temperatures up to 400 °C and no formation of intermetallic phases was observed even after 100 h of annealing. At higher temperatures, the intermetallic phases are formed and the time of the first observation of the inter-metallics is strongly dependent on time. The only intermetallic phase observed by the XRD was NiAl3. The content of other intermetallic phases clearly visible on the SEM micrographs was probably lower that the detection limit of the XRD. The forming layers of intermetallics are not protecting barrier and the reaction continue until the whole amount of Ni reacts, as was proven by observation of the sample annealed for 100 h at 550 °C.