材料科学
合金
冶金
微观结构
扫描电子显微镜
铝
渗氮
腐蚀
陶瓷
能量色散X射线光谱学
激光器
复合材料
图层(电子)
光学
物理
作者
H.C. Man,Chi Tat Kwok,T. M. Yue
标识
DOI:10.1016/s0257-8972(00)00729-5
摘要
Laser surface alloying of SiC/Si3N4on AA6061 aluminium alloy was carried out using a 2-kW CW Nd-YAG laser. Different ratios of SiC and Si3N4 powders were mixed and the layers were preplaced by pasting. Subsequent laser surface melting of the layers gave a surface metal matrix composite (MMC). The microstructure, chemical compositions and phase identification of the modified layers were examined using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD), respectively. The laser surface alloyed MMCs of AA6061-SiC and AA6061-Si3N4 consisted of small amounts of Al4C3/Al4SiC4and AlN, respectively. For specimens alloyed with 100% Si3N4 (AA6061-Si3N4), the cavitation erosion resistance Re was improved by three times as compared to the AA6061 alloy whereas there was no significant improvement in Re of the specimen alloyed with 100% SiC (AA6061-SiC). The surface hardness of the specimens alloyed with SiC/Si3N4 was increased seven times. All the laser alloyed specimens with SiC/Si3N4 showed a decrease in pitting resistance and absence of passivity owing to the aluminium–ceramic interfaces, which favour pit initiation or hindered passivity.
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