Formation of Yb α-SiAlON whiskers by heat treatment of hot-pressed bulk samples

Novel α-SiAlON whiskers with various morphologies were produced at the surface of hot-pressed bulk samples by heat treatment at an elevated temperature of 1800 °C. Other than straight whiskers with or without nodules on their heads, curved bow-like and kinked whiskers were also observed. The growth mechanisms of different whiskers were discussed in detail, and it was proposed that the VLS (vapour–liquid–solid) mechanism was the predominant growth mode responsible for the formation of a majority of whiskers. With continuous vaporization and consumption by reactions, the liquid droplet necessary for VLS would be exhausted in some cases, and at this time VS mechanism could also become active.