通过光学显微镜、X 射线衍射和扫描电镜等表征手段，研究流变加工的 ADC12合金的显微组织演变和力学性能。结果表明：流变铸造和流变压铸下初生铝树枝晶得到破碎，其平均颗粒尺寸、固相率随浇注温度降低而提高。流变加工有效地提高合金的力学性能。流变铸造条件下，合金抗拉强度随着浇注温度降低而提高，在580到600°C 之间浇注可以获得较高的力学性能。流变压铸条件下，595°C 浇注可以获得最佳的抗拉强度和伸长率。流变加工对 ADC12合金力学性能的提高主要在于实现致密度的提高和初生铝的圆整化。流变铸造和流变压铸工艺下初生铝平均颗粒尺寸与屈服强度可以通过 Hall?Petch 公式描述。
Microstructure evolution and mechanical properties of the rheo-processed ADC12 alloy were investigated by means of optical microscopy, X-ray diffraction and scanning electron microscopy. Primary dendritic Al of rheo-casting (RC) and rheo-diecasting (RDC) ADC12 alloys are sheared off. The average size, as well as solid fraction of the primary Al increase with descending pouring temperature. The mechanical properties of alloys are strengthened by rheo-processing. Ultimate tensile strengths of RC samples increase with the decrease of the pouring temperature, and reach the maximum in the range from 580 to 600 °C. At pouring temperature of 595 °C, the RDC sample obtains the best ultimate tensile strength and elongation. Great reductions on porosity and primary Al globularization are crucial to the mechanical properties. Relationships of the primary Al size and yield stress are depicted with Hall?Petch equation.
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