Composition and Properties of Hot‐Pressed SiC‐AIN Solid Solutions

Abstract

High‐density SiC‐AIN compositions were fabricated from powder mixtures by hot‐pressing in the 1700° to 2300°C temperature range. At 2100°C, a 2H solid solution was found from =35 to 100 wt% AlN. The single‐phase solid solution samples had steep composition gradients of >10%/μm within the grains. Lattice parameters closely followed Vegard's law. For compositions with <35% AIN, multiphase assemblages were found. Increasing grain size was observed for increasing firing temperature for SiC and AIN. Grain size of the solid solutions was significantly smaller than for SiC or AIN fired to the same temperature. Microhardness values decreased linearly in the solid solution region with increasing AIN content. Flexural strengths of SiC and AIN decreased with increasing firing temperature and increasing grain size. The strengths of SiC, AIN, and the solid solutions were low for materials hot‐pressed at 2100°C.