Bi对Al-Si活塞合金性能和组织的影响

Effects of Bi on Microstructure and Properties of Al-Si Piston Alloy

在Al-Si活塞合金中加入Bi元素,通过分析检测发现,Bi与Al形成偏晶转变,其在组织中以弥散的纯Bi独立相存在。由于Bi的特殊物理性能以及自润滑性,使Al-Si合金的尺寸稳定性和耐磨性得到提高,在共晶Al-Si合金中试样尺寸变化率降低了26.3,在过共晶Al-Si活塞合金中尺寸变化率降低了7.7～9.0,加Bi的过共晶Al-Si活塞合金的磨损量减少50左右。

Effects of Bi on microstructure and properties of Al-Si piston alloy were observed by SEM(scanning electronic microscope),OM(optical microscope) and tensile testing.The results show that Bi element can form monotectic transition with Al,and it exists as dispersive Bi phase independently in the microstructure of Al-Si piston alloy.The dimensional stability and wear resistance of the Al-Si piston alloy are greatly improved due to the special physical property and self-lubricity of Bi particle.The dimensional change rate of eutectic Al-Si piston alloy is decreased by 26.3% and of hypereutectic Al-Si piston is decreased by 7.7%～9.0%.In addition,the wear resistance of hypereutectic Al-Si piston alloy with Bi is decreased by approximately 50%.