The numerical method is employed to simulate the preparation process and investigate the mechanism of the nucleation inhibition with the effects of the Gibbs energy, clusters and interfacial energy, as well as the parameters for the dynamics such as viscosity and the cooling rate being considered.The suction casting of the bulk metallic glass formation is modeled and simulated. The results show that temperature at the bottom of the sample firstly drops and then rises back to 695K which is rather higher than the glass transition temperature. The crystalline phase precipitates in the center of the sample. The crystalline fraction reaches the highest value of 0.014 in the center of the sample. And the casting temperature should be lower than 1350K, the diameter of sample should be smaller than 45mm and the filling velocity should be lower than 4.29m/s.A new Gibbs energy model is developed by taking into account the characteristic of the bulk metallic glasses melts. With this model the Gibbs energy distributions within the compositions of Zr-based systems are obtained, and the well-known Zr-Al-Ni-Cu glass alloys are all in the composition regions with lower Gibbs energy.A Gibbs energy model of glass melt with multi-clusters is presented based on the statistical mechanism. The Gibbs energy drops about 4000J/mol at xNi=0.35 if the effect of cluster Zr2Ni is considered or about 8000 J/mol at xNi=0.40 if both of clusters Zr2Ni and ZrNi are taken into account.A new model for the interfacial energy of glass alloys is developed with the non-structural approach by investigating the effect of the enthalpy, the entropy and the compositions of liquid/crystal. The obtained higher interfacial energy regions of the Zr-based alloys are in good coincidence with the composition ranges with higher glass-forming ability. To Zr66Al8Cu7Ni19 alloy the interfacial energy increases about 0.045-0.07J/m2 due to the existence of clusters and the solution redistribution.The computed results for Zr-based bulk metallic glass alloys show that the nucleation rate of Zr66Al8Ni26 drops about 106 due to the existence of the clusters. Additionally, the higher cooling rates also lower the nucleation rate; To Pd82Si18 the peak value of nucleation rate falls to 104mol-1s-1 when the cooling rate increases to 103Ks-1. As the cooling rate reaches 102.5Ks-1, the peak value of nucleation rate of Zr65Al7.5Ni10Cu17.5 decreases to 105mol-1s-1.
修改评论