Characterization of LaB6 particulate-reinforced eutectic Al-12.6 wt% Si composites fabricated via mechanical alloying and spark plasma sintering

Abstract

Abstract In this study, x wt% LaB6 (x = 0, 2, 5 and 10) particulate-reinforced eutectic Al-12.6 wt% Si powders and composites were prepared from commercial Al, Si and LaB6 starting materials via powder metallurgy methods. Mechanical alloying (MA) was conducted on the blended powders using a high-energy ball mill (at 1060 cycles/min) for 2, 4 and 8 h. Mechanically alloyed (MA'd) powders were subjected to cold pressing (CP, under 450 MPa) and spark plasma sintering (at 450 °C for 180 s) processes. Powder particle morphologies changed from flaky to semi-equiaxial shape after MA duration of 4 h. Calculations performed through the XRD patterns of Al phase revealed that the average crystallite size increased and the average lattice strain decreased with increasing MA duration and LaB6 content. Spark plasma sintered (SPS'd) samples were examined in terms of composition, microstructure, densification and mechanical properties (hardness, yield strength, compressive strength and wear volume loss). Studies revealed that 4 h was the optimal MA duration and 10 wt% was the optimal reinforcement content for the LaB6particulate-reinforcedAl-12.6 wt% Si composites with respect to their mechanical properties. Al-12.6 wt% Si-10 wt% LaB6 sample had the highest hardness (1.72 ± 0.12 GPa), yield strength (373 MPa), compressive strength (578 MPa) and lowest wear rate (0.001 mm3/Nm) values among all SPS'd samples.