INFLUENCE OF SUPERHEAT AND HAMMER SPEED ON THE FORMATION OF METALLIC GLASSES

The effect of superheat on the formation of Fe80B20 and Pd80Si20 metallic glasses in the shock tube and hammer and anvil RST techniques was determined. The strong effect of increased superheat on the thickness and corresponding cooling rate in the quenched alloys supports the RST models of Kroeger et al. [2] and Megli, Eddingfield and Brower [3] wherein the fluid flow and heat flow were shown to be decoupled during rapid quenching. These models predict an expanded range for interface controlled heat transfer which covers the thickness range experienced in most rapid quenching techniques. Additionally, this work shows the strong effect of increased hammer speed on decreasing the as-quenched thickness and increasing the ease of glass formation in these two alloys.