Ce-Ga-Cu系非晶合金的热力学研究

Study on the Thermodynamics of Ce-Ga-Cu Bulk Metallic Glasses

通过差示扫描量热仪(DSC)利用三线法求出Ce_(70)Ga_xCu_(30-x)(x=4,6,10,12,15)系非晶合金过冷液体、熔体和晶体的热容及液体和晶体的热容差(ΔCP),并计算出液体相对于晶体的过剩焓(ΔHexc)、过剩熵(ΔSexc)和Gibbs自由能之差(ΔGl-s)。结果显示,对应于Ce-Ga-Cu系非晶合金低的玻璃转变温度(Tg),其液体的Kuazmann温度(TK)也较低。Ce-Ga-Cu系非晶合金的热力学参数ΔHexc、ΔSexc和ΔGl-s都随着Ga含量的增加而减小,这与玻璃形成能力(GFA)的变化趋势不相符。这说明对于Ce-Ga-Cu非晶合金体系,热力学驱动力不是控制非晶形成的主要因素,其他因素(比如动力学因素)可能是形成能力的关键因素。

Specific heat capacity and the heat capacity difference between liquid and crystalline of Ce70GaxCu30-x （x=4,6,10,12,15） bulk metallic glasses were obtained by differential scanning calorimeter（DSC） in reference to the specific heat capacity of a sapphire standard. Subsequently, enthalpy, entropy and Gibbs free energy of the undercooled liquid with respect to the crystalline were calculated according to above data. Results reveal that Ce-Ga-Cu bulk metallic glasses had low Kuazmann temperature correspond to their low glass transition temperature. Meanwhile, the three thermodynamic parameters including △H^exc, △S^exc and △^Gl-s decreased along with the increase of Ga. From the foregoing, it was found that the tendency of three parameters with the content of Ga was different from that of glassforming ability. This illustrates that the thermodynamic driving force is not major factor in glass-forming progress of Ce70GaxCu30-x （x= 4,6,10,12,15） bulk metallic glasses. The other element such as kinetics may play important roles to glass-forming ability.