铸造铝合金激光表面改性金属-陶瓷梯度层

Metal-ceramic Surface Gradient Layer Produced by Laser Cladding on Al-Si Allog

利用 5kWCO2 横流激光器对铸造铝合金表面先后预置不同成分粉末进行两次激光辐照扫描 ,成功地制备了Ni/WC和Cr/WC表面改性梯度层 ,并运用XRD、EDXS和SEM方法对激光表面改性梯度层的组织结构进行观察分析。发现经第二次激光扫描过程后在激光改性梯度层中因合金元素之间的反应 ,产生了大量的金属间化合物 ,激光改性梯度层的组织除α Al、Si和WC外 ,在Ni/WC激光改性梯度层中 ,金属间化合物主要为Al3 Ni2 和Ni3 Al,Cr/WC激光改性梯度层的金属间化合物为Al9Cr4 和Cr9Al17。另外 ,显微硬度测试表明 ,自基体至改性层表面激光改性梯度层内显微硬度呈现连续变化趋势 。

Ni/WC and Cr/WC laser surface modified gradient layers were prepared using twice laser scanning technique. The microsturcture of the laser surface modified gradient layers was investigated using XRD, EDXS and SEM. It was found that there were intermetallic compounds in the laser surface gradient layers due to the interactions between the metal elemtnts during the second laser cladding. The microsturcture of the modified gradient layers was composed of α Al matrix phase, WC particles and intermetallic compounds. In the surface of Ni/WC laser modified gradient layer the intermetallic compound was Al 3Ni 2 and Ni 3Al, while in the surface of Cr/WC laser modified gradient layer there were Al 9Cr 4 and Cr 9Al 17 . Furthermore, the microhardness of the gradient layers changed gradually from surface coating to substrate, while there was an abrupt change of mocrohardness in the single laser surface alloying coating.