Stability of amorphous metallic alloys

Abstract

In a previous paper it was concluded that the migration of phosphorus was causing the embrittlement of amorphous Fe₄₀Ni₄₀P₁₄B₆ at temperatures as low as 100 °C. In this paper we compare the stability of the above alloy to amorphous Fe₄₀Ni₄₀B₂₀, Fe₅₀Ni₃₀P₁₄B₆, and Fe₅₀Ni₃₀B₂₀. The stability is evaluated from brittleness measurements after annealing at temperatures between 100 and 400 °C. The results confirm the prediction that the removal of phosphorus suppresses the embrittlement at low temperatures; temperatures above 225 °C are required to cause embrittlement in the phosphorus‐free alloys. At higher temperatures the fracture strain approaches that of the phosphorus‐containing alloy. It is concluded that the replacement of P by B inhibits the low‐activation processes involved in the embrittlement process. The changes are not related to the changes in the glass transition temperatures.