Abstract In this study, hot-pressing technique was used to produce Al-5wt.% Cu-20vol.% SiC and Al-5wt.% Mg-20vol.% SiC particulate metal matrix composites. The powders were ball milled and the powder mixtures were hot pressed uniaxially under a pressure of 550 MPa at a temperature of 450 °C in vacuum atmosphere for different holding times of 30, 60 and 120 min. A common observation was that the density of Al composites decreased slightly with increasing hot press sintering time. The Al-5wt.% Cu-20vol.% SiC samples exhibited maximum density of ∼95.7% ρth (theoretical density) and Al-5wt.% Mg-20vol.% SiC composite was measured with maximum density of ∼97.8% ρth after hot pressing for 30 min. The XRD and SEM characterization confirms presence of Al, SiC and CuAl2 phases for Al-Cu-SiC. Whereas the microstructure of Al-Mg-SiC composite consists of Al0.95Mg0.05 solid solution phase along with SiC phase. Among all the compositions, a maximum hardness of 3.2 GPa was noted for the Al composites, which were hot pressed at 60 min. A comparison with the existing literature reveals the presently developed Al alloy composites exhibited superior hardness. Corrosion tests were carried out using potentiodynamic polarization and electrochemical impedance spectroscopy to study the corrosion behavior of both these hard composites in marine environment (3.5wt.% NaCl) at room temperature. The corrosion rate of the samples varied between 1.8 and 2.7 mpy (mils per year), particularly, Al-5wt.% Cu-20vol.% SiC composite showed better corrosion resistance. Further impedance spectroscopy analysis revealed that Al-Cu-SiC has relatively larger semi-circular diameter when compared to Al-Mg-SiC. These observations indicate that Al-Cu-SiC exhibits high polarization resistance than Al-Mg-SiC composite.

中文翻译：

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极硬Al-Cu/Mg-SiC轻金属合金复合材料的腐蚀行为

摘要 本研究采用热压技术制备Al-5wt.% Cu-20vol.% SiC和Al-5wt.% Mg-20vol.% SiC颗粒金属基复合材料。对粉末进行球磨，并将粉末混合物在 550 MPa 的压力和 450 °C 的温度下在真空气氛中单轴热压 30、60 和 120 分钟的不同保持时间。一个常见的观察结果是铝复合材料的密度随着热压烧结时间的增加而略有下降。Al-5wt.% Cu-20vol.% SiC 样品的最大密度为~95.7% ρth（理论密度），Al-5wt.% Mg-20vol.% SiC 复合材料在热后测量的最大密度为~97.8% ρth按压30分钟。XRD 和 SEM 表征证实了 Al-Cu-SiC 中存在 Al、SiC 和 CuAl2 相。而Al-Mg-SiC复合材料的微观结构由Al0. 95Mg0.05 固溶体相和 SiC 相。在所有成分中，铝复合材料的最大硬度为 3.2 GPa，热压时间为 60 分钟。与现有文献的比较表明，目前开发的铝合金复合材料表现出优异的硬度。使用动电位极化和电化学阻抗谱进行腐蚀测试，以研究这两种硬质复合材料在海洋环境 (3.5wt.% NaCl) 中室温下的腐蚀行为。样品的腐蚀速率在 1.8 到 2.7 mpy（密耳/年）之间变化，特别是 Al-5wt.% Cu-20vol.% SiC 复合材料表现出更好的耐腐蚀性。进一步的阻抗谱分析表明，与 Al-Mg-SiC 相比，Al-Cu-SiC 具有相对较大的半圆直径。