Al-12Si-2Cu-xCe压铸铝合金的微观组织演化及显微硬度

Microstructure Evolution and Microhardness of Die-casting Al-12Si-2Cu-xCe Aluminum Alloy

在工业用压铸铝合金Al-12Si-2Cu(ADC12)中分别添加0.3 wt%、0.6 wt%、0.9 wt%的稀土Ce元素,对其进行压铸实验。采用光学显微镜和显微硬度计,研究了Al-12Si-2Cu-xCe压铸铝合金的微观组织演化及显微硬度。实验结果表明:初生α-Al枝晶得到一定的球化,且其二次枝晶间距(SDAS)开始随着Ce含量的增加而逐渐减小;当Ce含量为0.6 wt%时,SDAS达到最小值;当Ce含量为0.9%时,SDAS值反而更大。另外,Ce的添加使α-Al枝晶间共晶Si相和富Fe金属间化合物相(β-AlFeSi)的尺寸变化规律与SDAS的变化规律类似。Al-12Si-2Cu-xCe(x=0、0.3、0.6、0.9)压铸铝合金对应的显微硬度值分别为100.6、109.87、111.54、108.1 HV。

The rare earth Ce was added into the industrial die-casting Al-12Si-2Cu aluminum alloy （ADC12） and the additions were 0.3wt%, 0.6wt% and 0.9wt%, respectively. The microstructural evolution and microhardness of the die-casting samples were examined by optical microscopy and microhardness tester. The experimental results show that the primary α-Al dendrites are spheroidized, and the secondary dendrite arm spacing （SDAS） of α-Al decreases with the increase of Ce content; as the Ce content increases to 0.6wt%, the lowest SDAS are obtained; as the Ce content increased to 0.9wt%, the value of SDAS is greater instead. In addition, the variations of sizes in the eutectic Si phase and the iron-rich intermetallics compounds （β-AlFeSi） are similar to that of the SDAS. The microhardness of the die-castings were measured, the microhardness corresponding to the die-cast samples with 0, 0.3wt%, 0.6wt% and 0.9wt% Ce additions are 100.6, 109.87, 111.54 and 108.1HV, respectively.