热处理对SiC_p/Al2124复合材料显微组织与耐蚀性的影响

为提高 Si C颗粒增强铝基复合材料 Al 2 12 4的耐蚀性 ,采用 X射线衍射、扫描电镜和电化学测试等手段 ,研究了 3种热处理工艺 (T1,T4和 T6 )对复合材料中第二相化合物的析出状况以及该材料在 Na Cl水溶液中的腐蚀行为的影响。结果表明 ,在 T1状态下 ,铝合金基体内及 Si Cp/铝合金界面上析出大量以 Cu Al2 为主的第二相化合物 ,导致复合材料表面点蚀活性位置增多 ,点蚀敏感性增大 ;但是 ,T6和T4热处理显著减少 Cu Al2 相析出并大幅度降低复合材料的点蚀敏感性。 3种热处理状态下 Si Cp/Al 2 12 4复合材料的耐点蚀性能可依下列顺序提高 :T1,T6 ,T4。

Effect of heat treatment on microstructure and corrosion resistance of SiC_p/Al2124 composite

The corrosion resistance of Al 2124 based composite that was reinforced with 17 vol.% SiC particles was analyzed by investgating the effects of three heat treating technologies (T1, T4, and T6) on the precipitation of secondary phase compounds in the composite and on the corrosion behavior of the composite in mass fraction 3.5% NaCl aqueous solution. The effects were analyzed using X ray diffraction, scanning electron microscopy and electrochemical measurements. The result showed that the T1 heat treatment precipitated large amounts of secondary phase compounds, consisting mainly of CuAl 2 , both in the aluminum alloy matrix and at the interfaces of SiC p/Al, leading to an increase in the number of active pitting sites on the surface of the composite and to enhancement of the composite's sensitivity to pitting. The T6 and T4 heat treatments, however, significantly reduced the amount of CuAl 2 precipitates, and hence, greatly decreased the sensitivity of the composite to pitting. Therefore, the pitting corrosion resistance of the SiC p/Al 2124 composite can be improved the most by using the T4 heat treating technology with some improvement using the T6 technology.