Zr_(50)Cu_(50)金属玻璃形成过程中自由体积与玻璃态转变温度关系的分子动力学模拟

Relationship Between Free Volume and Glass Transition Temperature of Zr_(50)Cu_(50) Metallic Glasses Based on Molecular Dynamics Simulation

利用分子动力学模拟了Zr50Cu50金属玻璃的形成过程,并获得了不同温度下合金的原子构型.借助金属玻璃中自由体积量等于金属玻璃与对应晶体的体积差理论提出一种自由体积湮没速度法,对Zr50Cu50金属玻璃形成过程中的临界玻璃态转变温度Tc以及热力学玻璃态转变温度Tg进行预测.用该方法确定出的Tc(969.5K)与利用模式耦合理论计算获得的Tc(978.4K)接近;Tg(731K)与利用平均原子体积随温度变化关系曲线确定的Tg(725K)相近.运用自由体积湮没速度法计算的Tc和Tg无需计算各温度下的原子扩散系数,节省了计算时间.

Atomic structure evolution and diffusivity during the cooling of Zr50Cu50 metallic liquid are studied by molecular dynamics（MD） simulation.Based on the theory that free volume is equal to the volume difference between the amorphous materials and their crystalline counterpart,a new method of annihilating rate of free volume has been developed and applied to predict the critical microscopic glass transition temperature.The predicted critical temperature Tc was 969.5 K,which is close to the MCT（mode-coupling theory） value of 978.4 K,and the caloric glass transition temperature Tg was 731 K,which is also close to the value of 725 K determined from the curve of average atomic volume with temperature.Without calculation of diffusion coefficients at a serial of specified temperatures,the developed method is more convenient than former methods to calculate Tc and Tg.