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本文采用自行改装设计的固液态力学性能测试装置时铸造Al-Cu合金在固液态时的强度和塑性进行了研究。考察了温度、铜含量、稀土La、低熔点杂质以及不同变形速度对合金在固液态时的强度和塑性的影响。研究结果表明合金在固液态时由于液体在晶间的分布,呈现出明显的热脆弱区,强度和塑性值都很低,是铸件形成热裂纹的主要原因。加入微量稀土La可以强化晶界,减少热脆弱程度,而低熔点杂质及提高变形速度增加热脆弱程度。
In this paper, the strength and ductility of Al-Cu alloy cast in solid-liquid state during self-designed solid-liquid mechanical testing device was studied. The effects of temperature, copper content, rare earth La, low melting point impurities and different deformation rates on the strength and ductility of the alloy in solid-liquid state were investigated. The results show that due to the distribution of the liquid in the intergranular phase, the alloy exhibits obvious hot and brittle zones with low strength and plasticity, which is the main reason for the formation of hot cracks in the castings. Adding rare earth La can strengthen the grain boundary and reduce the degree of thermal fragility, while the low melting point impurities and increase the deformation speed increase the degree of thermal fragility.