Al–5.7Si–2Cu–0.3Mg alloy was subjected to a thixoforming process. The impact behaviour of the thixoforming process on microstructure characterisation and mechanical properties was investigated. A cooling slope (CS) technique was applied here to get thixoforming feedstock material at three different pouring temperatures of 640 °C, 650 °C and 660 °C, plate lengths 300 mm, 400 mm and 500 mm and constant CS angle 60°. Some samples of thixoformed were treated using T6 heat treatment. These samples were characterised via optical microscopy, scanning electron microscope, energy dispersive spectrometer and X-ray diffraction investigations, tensile and hardness tests. Consequently, the optimum conditions of CS casting process were 650 °C pouring temperature and 400mm plate length. The thixoformed alloys observed fine globular α-Al phase microstructure surrounded by uniformly distributed Si particle, minimum of porosity and refined fragmented intermetallic phase. The hardness of the thixoformed-T6 sample was roughly twice as much as-cast sample. The tensile and yield strength of thixoformed-T6 samples were enhanced by 45% and 39%, respectively, compared to as-cast samples. The thixoformed-T6 samples observed the highest value of tensile elongation to fracture of 4.8 ± 0.4%. The tensile fractures surface of thixoformed-T6 samples exhibited decline in each of tensile strength and ductility, due to occurrence of Fe-rich intermetallic on the samples.

Graphic abstract

中文翻译：

---

触变性Ai–5.7Si–2Cu–0.3Mg铝合金的显微组织评估和力学性能

Al–5.7Si–2Cu–0.3Mg合金经历了触变性成型。研究了触变成型工艺对组织表征和力学性能的影响。此处采用了冷却斜率（CS）技术，以在640°C，650°C和660°C的三种不同浇注温度，板长300 mm，400 mm和500 mm以及恒定CS角60°的条件下获得触变成型原料。使用T6热处理处理了一些触变性样品。通过光学显微镜，扫描电子显微镜，能量分散光谱仪和X射线衍射研究，拉伸和硬度测试对这些样品进行了表征。因此，CS浇铸工艺的最佳条件是浇铸温度为650°C，板长为400mm。触变合金观察到细小的球状α-Al相的微观结构，被均匀分布的Si颗粒包围，孔隙率最小，金属间碎相细化。触变T6样品的硬度大约是铸造样品的两倍。与铸态样品相比，触变T6样品的拉伸强度和屈服强度分别提高了45％和39％。触变T6样品的断裂断裂伸长率最高，为4.8±0.4％。触变T6样品的拉伸断裂表面表现出拉伸强度和延展性均下降，这是由于在样品上出现了富铁金属间化合物。触变T6样品的硬度大约是铸造样品的两倍。与铸态样品相比，触变T6样品的拉伸强度和屈服强度分别提高了45％和39％。触变T6样品的断裂断裂伸长率最高，为4.8±0.4％。触变T6样品的拉伸断裂表面表现出拉伸强度和延展性均下降，这是由于在样品上出现了富铁金属间化合物。触变T6样品的硬度大约是铸造样品的两倍。与铸态样品相比，触变T6样品的拉伸强度和屈服强度分别提高了45％和39％。触变T6样品的断裂断裂伸长率最高，为4.8±0.4％。触变T6样品的拉伸断裂表面表现出拉伸强度和延展性均下降，这是由于在样品上出现了富铁金属间化合物。

图形摘要