Zr_(57.5)Cu_(27.3)Al_(8.5)Ni_(6.7)非晶合金的非等温和等温晶化动力学研究

对制备的Zr_(57.5)Cu_(27.3)Al_(8.5)Ni_(6.7)非晶合金的等温与非等温晶化动力学通过差式扫描量热法(DSC)进行了研究,根据Kisinger方程计算出Zr_(57.5)Cu_(27.3)Al_(8.5)Ni_(6.7)非晶合金在非等温条件下的激活能Eg,Ex,Ep1和Ep2,分别为409.70kJ/mol(±60.07kJ/mol),335.53kJ/mol(±39.94kJ/mol),323.95kJ/mol(±15.21kJ/mol)和187.75kJ/mol(±13.27kJ/mol).在718K,723K,728K和733K等温条件下得到的晶化体积分数与时间的关系曲线呈"S"型,表明晶化过程为典型的形核长大型转变.Avrami指数n的范围为3≤n≤4,表明晶化过程由界面控制的二维长大转变为界面控制的三维长大,形核率随时间逐渐降低至稳定,等温晶化过程得到的激活能平均值434.81kJ/mol,高于非等温晶化过程的有效激活能.

Isochronal and Isothermal Crystallization in Zr57.5Cu27.3Al8.5Ni6.7 Bulk Metallic Glass

Non-isothermal crystallization transformation kinetics and isothermal crystallization kinetics of prepared Zr57.5Cu27.3Al8.5Ni6.7 bulk metallic glass (BMG) were investigated with differential scanning calorimetry (DSC). In isochronal mode, the values of activation energy, Eg, Ex, Ep1 and Ep2, calculated by Kisinger method are 409.70 kJ/mol (± 60.07 kJ/mol), 335.53 kJ/mol (± 39.94 kJ/mol), 323.95 kJ/mol (± 15.21 kJ/mol) and 187.75 kJ/mol (± 13.27 kJ/mol), respectively. In isothermal mode, the S-shape relation curves of crystalline volume fraction and temperature reveal the typical transition of nucleation and growth. The Avrami exponent n ranges from 3.0 to 4, indicating the crystallization mechanism in the Zr57.5Cu27.3Al8.5Ni6.7 BMG is mainly interface-controlled. The crystal growth way changes from two-dimensional growth with decreased nucleation rate to three-dimensional growth in the isothermal crystallization process. In isothermal mode, the mean value of activation energy is 434.81 kJ/mol, which is higher than that in the isochronal mode.