Al–Cr–Fe quasicrystals as novel reinforcements in Ti based composites consolidated using high pressure spark plasma sintering

Abstract

Ti based metal matrix composites (MMCs) reinforced with Al–Cr–Fe quasicrystals have been prepared using high pressure spark plasma sintering (HP-SPS) with a high heating/cooling rate of 200°C/min between 550°C and 750°C and without any isothermal process. As the sintering pressure increases, the compositional variation of Al–Cr–Fe reinforcements diminishes. It is found that under a sintering pressure of 250MPa, the phases in Al–Cr–Fe powders, including two quasicrystals, decagonal Al–Cr–Fe and icosahedral Al–Cr–Fe, and two of their approximants, Al9(Cr,Fe)4 and Al8(Cr,Fe)5, can be preserved. An interfacial layer forms between Ti matrix and Al–Cr–Fe reinforcements in the sintering process. This interfacial layer consists of Al3Ti and AlTi. The incorporation of 20wt.% Al–Cr–Fe particles into Ti matrix was found to improve the microhardness to Hv 480 and reduce the wear rate by around 70%. This implies that Al–Cr–Fe is a promising reinforcement candidate for Ti.