Figure 7
Temperature curves (a), Young’s modulus (b), hardness (c) and true density (d) of different input power specimen. Note that the temperatures in (a) correspond to the outer surface temperature of the crucible. The solid dots indicate the time when the hotspot caused by thermal runaway appeared on the crucible surface in 4 min for 1000 W, 3 min for 800 W and 600 W, 14 min for 400 W, and 10 min for 250 W specimen. The size and colour of the hotspot glow appear to reduce gradually from 1000 to 250 W. For example, the hotspot glow of the 1000 W sample was a bright yellow colour and > 2 cm in diameter, while that of the 250 W sample was a dimmed red colour with less than 1 cm diameter. The estimated temperature of the hotspot glows are between 1700 and 2200 °C depending on the sample mass and input power based on the previous numerical simulation study14.
