Crystallization of amorphous Zr-Be alloys

Abstract

The thermal stability and structure of binary amorphous Zr_{100 − x} Be _x alloys have been studied using differential scanning calorimetry and neutron diffraction over a wide concentration range (30 ≤ x ≤ 65). The amorphous alloys have been prepared by rapid quenching from melt. The studied amorphous system involves the composition range around the eutectic composition with boundary phases α-Zr and ZrBe₂. It has been found that the crystallization of alloys with low beryllium contents (“hypoeutectic” alloys with x ≤ 40) proceeds in two stages. Neutron diffraction has demonstrated that, at the first stage, α-Zr crystallizes and the remaining amorphous phase is enriched to the eutectic composition; at the second stage, the alloy crystallizes in the α-Zr and ZrBe₂ phases. At higher beryllium contents (“hypereutectic” alloys), one phase transition of the amorphous phase to a mixture of the α-Zr and ZrBe₂ phases has been observed. The concentration dependences of the crystallization temperature and activation energy have been revealed.