Effect of Cu on rapidly solidified Al-Mn-Be alloy

The microstructure of an Al-Mn-Be-Cu alloy was characterised after melt spinning and heat-treatment at different temperatures. The optimised melt-spinning parameters made it possible to obtain ribbons with thicknesses ranging from 30 to 200 ?m, having a microstructure composed of a supersaturated Al-rich solid solution, finely dispersed icosahedral quasicrystalline (IQC) particles, and a small fraction of Al2Cu. The finest dispersion of the IQC-particles, and consequently the highest microhardness, was obtained on the wheel-side. The initial microstructure started to decompose at temperatures around 400 °C. The IQC-phase was replaced by the intermetallic compounds ?1-Al29Mn6Cu4 and Be4Al(Mn,Cu). The maximum hardness of the ribbons, which was approximately 50% higher than in the as-cast state, was attained after heat treatment at 400 °C, and could be attributed to the fine dispersion of ?1-Al29Mn6Cu4 and IQC-particles.