As the most popular magnesium alloy, AZ91 is desired in the automotive-related manufacturing industry because of its high specific strength and good corrosion resistance. AZ91-based automotive components are made by conventional high-pressure die casting (C-HPDC) and are unable to provide adequate mechanical properties to components with heavy cross sections because of the high level of gas and shrinkage porosity in C-HPDC parts. To expand the usage of AZ91, a replacement for the C-HPDC to minimize the porosity content is needed. In this research, Mg alloy AZ91 with a cross-sectional thickness of 10 mm was squeeze cast (SC) under an applied pressure of 90 MPa. A counterpart was made by C-HPDC for comparison with SC AZ91. The porosity of the SC and C-HPDC AZ91 specimens was evaluated by optical microscopy and density measurements. The SC AZ91 was almost pore free, whereas the counterpart had a porosity of 3.57%. Microstructural analyses by scanning electron microscopy showed that the SC and C-HPDC AZ91 contained phases of primary α-Mg, β-Mg₁₇Al₁₂ eutectic and Al-Mn intermetallic. Tensile testing indicated that the ultimate tensile strength and elongation (e_f) of the SC alloy were 171.7 MPa and 3.0%, which resulted in improvements of 33 and 77% compared with those of the C-HPDC counterpart. The strain-hardening rate and tensile toughness of the SC AZ91 during deformation were higher than those of the HPDC specimen. SEM fractography revealed characteristics of plastic deformation on the flat fractured surface of the SC AZ91, whereas brittle fracture prevailed on the HPDC counterpart.

作为最受欢迎的镁合金，AZ91因其高比强度和良好的耐腐蚀性而在汽车相关制造行业中广受欢迎。基于AZ91的汽车零部件是通过传统的高压压铸（C-HPDC）制造的，由于C-HPDC零部件中的气体含量高且收缩孔隙率高，因此无法为具有较大横截面的零部件提供足够的机械性能。为了扩大AZ91的用途，需要使用C-HPDC的替代品以最大程度地减少孔隙率。在这项研究中，在90 MPa的施加压力下，挤压铸造（SC）横截面厚度为10 mm的Mg合金AZ91。C-HPDC制作了一个副本，用于与SC AZ91进行比较。通过光学显微镜和密度测量评估SC和C-HPDC AZ91标本的孔隙率。SC AZ91几乎没有孔，而对应的孔度为3.57％。扫描电子显微镜的显微结构分析表明，SC和C-HPDC AZ91包含初级α-Mg，β-Mg相₁₇ Al ₁₂共晶和Al-Mn金属间化合物。拉伸试验表明，SC合金的极限拉伸强度和伸长率（e _f）分别为171.7 MPa和3.0％，与C-HPDC相比，分别提高了33％和77％。变形期间SC AZ91的应变硬化率和拉伸韧性高于HPDC试样。SEM断层扫描显示SC AZ91的平坦断裂表面具有塑性变形的特征，而HPDC对应物则普遍存在脆性断裂。