Crystallization of amorphous Zr–Be alloys

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 $\le x\le$ 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 $\alpha$-Zr and ZrBe$_2$. It has been found that the crystallization of alloys with low beryllium contents (“hypoeutectic” alloys with $x\le$ 40) proceeds in two stages. Neutron diffraction has demonstrated that, at the first stage, $\alpha$-Zr crystallizes and the remaining amorphous phase is enriched to the eutectic composition; at the second stage, the alloy crystallizes in the $\alpha$-Zr and ZrBe$_2$ phases. At higher beryllium contents (“hypereutectic” alloys), one phase transition of the amorphous phase to a mixture of the $\alpha$-Zr and ZrBe$_2$ phases has been observed. The concentration dependences of the crystallization temperature and activation energy have been revealed.