中文摘要：

为了探索合金熔体结构与凝固组织的相关性，改善Al-Cu系合金的组织性能，使用四探针电阻法研究了Al-6％Cu合金升温过程中的电阻率行为。结果表明，在熔体过热处理温度区间该合金存在明显的电阻率突变现象，暗示在该阶段合金熔体发生了温度诱导的结构转变。合金金相组织观察和力学性能测试表明，该结构转变使得合金凝固组织晶粒尺寸明显细化、晶粒形貌趋于等轴化；在过热处理后，合金屈服强度提高了约18％，表面洛氏硬度提高了约14％。

英文摘要：

To explore the relativity of the melt structure and the solidification microstructure of alloy, and to improve microstructure and property of Al-Cu system alloy, the resistivity behaviors of Al-6% Cu alloy in the heating process were researched by using the four-probe electric-resistivity method. The results show that there is a phenomenon of abrupt resistivity in the alloy at the melt superheating treatment temperature interval, which hints that the alloy melt structure produces the change of temperature induced structure in the stage. The microstructure observation and the experiment of mechanical properties show that the structure change makes the grain size of solidification microstructures of the alloy gets refinement, and grain morphology tends to equiaxed grain; the alloy yield strength increased about 18%, and the Rockwell hardness increased about 14% after superheating treatment.