三种模锻工艺成形AZ91D镁合金的组织和力学性能

Microstructures and Mechanical Properties of AZ91D Magnesium Alloy in Three Kinds of Die Forging Forming

研究了液态模锻、流变模锻和触变模锻生产的AZ91D镁合金锻件的组织及力学性能。结果表明:这三种模锻件的显微组织均是由α-Mg和β-Mg17Al12相组成,但它们的形状、大小、数量和分布有所不同,并不同程度地影响了模锻件的力学性能。通过扫描电子显微镜对拉伸断口形貌进行了观察并进行了能谱分析。结果表明,裂纹主要源于脆性共晶相β-Mg17Al12的断裂;这三种模锻件的拉伸断口虽然都属于沿晶断裂,但断口形貌却有很大的不同。

Microstructures and mechanical properties of AZ91 D magnesium alloy forgings produced by liquid forging,rheoforging and thixoforging were studied. The results show that although the microstructures of the three forging parts are all composed of α-Mg and β-Mg17Al12 phases, their shapes, sizes, numbers and distributions are all different, which influences the mechanical properties of die forgings in different degrees. The tensile fracture morphologies were observed and their energy spectrums were analyzed by scanning electron microscopy. The results show that the cracks are mainly originated from the brittle fracture of the β-Mg17Al12 eutectic phases. Although the tensile fracture surfaces of the three forging parts all belong to the intergranular fracture, their fracture morphologies are greatly different.