Zr_(x)TiNiCuBe高熵非晶合金的晶化动力学  

Crystallization Kinetics of Zr_(x)TiNiCuBe High-Entropy Bulk Metallic Glasses

作　　者：王彦芳 何雅茹 胡方裕 石志强 Wang Yanfang;He Yaru;Hu Fangyu;Shi Zhiqiang(School of Materials Science and Engineering,China University of Petroleum(East China),Qingdao 266580,China)

机构地区：[1]中国石油大学(华东)材料科学与工程学院,山东青岛266580

出　　处：《稀有金属材料与工程》2024年第11期3224-3232,共9页Rare Metal Materials and Engineering

基　　金：山东省自然科学基金(ZR2019MEM032)。

摘　　要：利用铜模铸造方法制备了Zr_(x)TiNiCuBe(x=1.5,2,2.5,3,3.5,at%)高熵非晶合金,采用差示扫描量热仪(DSC)对其晶化动力学进行了研究。结果表明,Zr_(x)TiNiCuBe高熵非晶合金的变温晶化为多级晶化过程,与升温速率具有明显动力学效应。利用Kissinger方程计算的变温晶化激活能,均表现为Eg>Ex>Ep_(1),Ep_(1)<Ep_(2)<Ep_(3),说明玻璃转变的原子重排过程比形核和长大更困难,等温晶化是一个由易到难的过程。随Zr含量增加,变温晶化激活能Eg先增大后减小。其中Zr_(2)TiNiCuBe的变温晶化激活能最大,热稳定性最好。等温晶化为单一晶化过程,晶化体积分数与时间呈“S”型曲线,为典型的形核长大型转变。利用Arrhenius公式计算了等温晶化激活能。随着Zr含量的增加,Zr_(x)TiNiCuBe的平均等温晶化激活能逐渐减小。利用Johnson-Mehl-Avrami(JMA)方程得出的Avrami指数n的范围为1.5≤n≤2.5,表明等温晶化过程为扩散控制并伴随着晶核成核速率降低的生长过程。Non-equiatomic Zr_(x)TiNiCuBe(x=1.5,2,2.5,3,3.5,at%)high-entropy bulk metallic glasses(HE-BMGs)were prepared by copper mold casting method,and the crystallization kinetics was studied by differential scanning calorimeter(DSC)under both non-isochronal and isothermal conditions.The non-isothermal crystallization kinetics of Zr_(x)TiNiCuBe HE-BMGs show a multiple-stage process.The characteristic temperatures increase with the increase in the heating rate,showing obvious kinetics effects.The activation energy calculated by the Kissinger equation shows an order of Eg>Ex>Ep_(1),indicating that overcoming the energy barrier for the rearrangement is more difficult than atoms nucleation process and the grain growth process of crystallization.The activation energy of crystallization event is in the order of Ep_(1)<Ep_(2)<Ep_(3),demonstrating the non-isothermal crystallization processing is from easy to difficult.The activation energy increases and then decreases with the increase in Zr content.Zr_(2)TiNiCuBe HE-BMG has a larger activation energy and better thermal stability than others.Isothermal crystallization shows a single exothermic behavior after different incubation periods.As isothermal temperature increases,incubation time decreases rapidly and the width of exothermic peak decreases markedly.The crystallization volume fraction(x)vs time(t)curves are typical“S”type.With the decrease in isothermal temperature,the x vs t curves become gentle,indicating that the process of crystallization slows down.The local crystallization activation energy for isothermal processing was calculated using the Arrhenius formula.With the increase in Zr content,the local crystallization activation energy gradually decreases and the thermal stability decreases.The Avrami exponent obtained by the Johnson-Mehl-Avrami(JMA)equation is between 1.5 and 2.5,indicating that the isothermal crystallization mechanism is mainly a diffusion-controlled growth process with a nucleation rate decrease.

关 键 词：高熵非晶合金 晶化动力学 变温晶化 等温晶化 晶化激活能 

分 类 号：TG139.8[一般工业技术—材料科学与工程]