【摘要】 通过显微组织和热物性能表征、热处理及第一性原理计算,研究Mg-2Zn-xCu (x=0.5, 1.0, 1.5,摩尔分数,%)合金的显微组织和热物性能。结果表明,添加Cu元素对合金显微组织和热物性能有影响。随着Cu含量增加,铸态合金中MgCuZn相含量增加,铸态合金电导率和热导率增大。固溶处理后,合金中共晶组织部分溶解,Zn原子回溶进入基体,导致合金的电导率和热导率均降低。时效处理前期,溶质原子从基体中沉淀析出,合金电导率增大,时效24 h后,Mg-2Zn-1.5Cu合金的热导率最高达到147.1 W/(m·K)。合金中形成的热稳定MgCuZn相对合金的电导率和热导率起促进作用。Zn元素在基体中含量越低,晶格畸变程度越低,导热性能则越好。另外,第一性原理计算结果也表明MgCuZn三元相具有很好的导电和导热性能。更多还原

【Abstract】 The microstructure and thermophysical properties of Mg-2 Zn-x Cu alloys(x=0.5, 1.0 and 1.5, at.%) were investigated through microstructural and thermophysical characterization, heat treatment, and first-principles calculations. It was found that the addition of Cu had influence on the microstructure and thermophysical properties of the alloy. As the Cu content increased, the content of the MgCuZn phase increased in the as-cast alloys along with the electrical and thermal conductivities. After solution treatment, the eutectic structure partially decomposed and Zn atoms dissolved into the matrix, leading to the decrease in both the electrical and thermal conductivities of the alloy. During the early stages of the aging treatment, solute atoms precipitated from the matrix, thus increasing the electrical conductivity of the alloy. After aging for 24 h, the thermal conductivity of Mg-2 Zn-1.5 Cu alloy reached the maximum of 147.1 W/(m·K). The thermostable MgCuZn phases were responsible for increasing the electrical and thermal conductivities. Smaller amounts of Zn atoms dissolved in the matrix resulted in smaller lattice distortion and higher conductivities. The first-principles calculations findings also proved that the MgCuZn phases had very high conductance.更多还原