晶粒细化对Cu-Si合金高温氧化行为的影响

Effect of Grain Size Reduction on High Temperature Oxidation of Cu-Si Alloys

采用电弧熔炼(CA)和机械合金化(MA)方法制备了晶粒尺寸差别较大的二元单相Cu-Si合金(CACu-0.6Si和MACu-0.6Si,CACu-3.6Si和MACu-3.6Si),并研究了它们在700和800℃纯O2中的高温氧化行为。用光学显微镜(OM)、X射线衍射仪(XRD)及带有能谱的扫描电子显微镜(SEM/EDX)等对合金组织、氧化膜形貌及组成等进行观察和分析。结果表明:2种方法制备的Cu-Si合金氧化后均形成了CuO→Cu2O→Cu2O+SiO2(富SiO2)→内氧化区结构的氧化膜,但未形成连续的SiO2保护膜。2种成分的机械合金化Cu-Si合金的氧化速度小于相同温度下同成分的熔炼Cu-Si合金。

The binary single-phase Cu-Si alloys with great difference in grain size have been prepared by conventional casting （CA） and mechanical alloying （MA） through hot pressing techniques, and their oxidation behaviors at 700 ℃ and 800 ℃ in pure 02 have been studied. The microstructures of the alloys, the cross sectional morphologies and the composition of the oxide scales were investigated by optical microscope （OM）, X-ray diffraction （XRD） and scanning electron microscope （SEM） with EDX. Results show that all the alloys formed similar complex scales like CuO--＊Cu20--＊Cu20＋SiO2 （rich in SiO2）--~internal oxidation zone, and did not form continuous layers of SiO2. Seen as a whole, the oxidation rates for the mechanically alloyed alloys were lower than those of the corresponding cast alloys. The differences in oxidation rates are attributed to that the grain-size reduction may enhance the diffusivity of Si. The formation rates of zones rich in SiO2 can be enhanced, and it can effectively restrain the quick formation of copper oxides.