钠盐变质及振动对Zn - 27Al - Si合金组织和性能的影响

为了提高锌铝合金在干摩擦条件下的耐磨性以进一步拓宽其应用范围,在Zn-27Al合金中加入3%～4%Si,并通过钠盐变质及振动处理,制得Zn-27Al-Si合金.利用显微镜和电镜观察分析了试验合金中硅相形貌,并对合金的力学性能进行了测定.研究结果表明:钠吸附在硅晶体的生长台阶上使初晶硅产生大量分枝,最终生长成为球团状;振动一方面改变了结晶的温度场,抑制了共晶硅的析出,另一方面产生的"扰动"作用使硅球表面辐射生长的杆状共晶硅机械碎断,从而减少了硅相对基体的割裂作用,使试验合金在其他性能不变的情况下耐磨性提高3～4倍.

Effects of the modification with sodium salt and vibration on microstructure and properties of Zn-27Al- Si alloy

In order to improve the wear-resistance performance of Zn - Al alloy on the condition of dry friction and to widen its application in industry, the Zn -27Al-Si alloy was prepared by adding 3% -4% silicon to the alloy and then treating it with modifying agent containing sodium and vibration. Through optical microscope and electron microscope the morphology of silicon phase was observed, the mechanical properties of the alloy were tested. The results indicated that sodium adsorbing on the growth sidestep of silicon crystal resulted in primary silicon changed into nodular silicon. On the hand, vibration can alter the temperature field of crystallization and restrain the precipitation of eutectic silicon. On the other hand, vibration can mechanically break up stick-form eutectic silicon that grew radiated on the surface of nodular silicon and decrease the separation of the silicon phase to the alloy matrix. The results of dry friction test showed that the wear-resistance Zn -27Al - Si alloy was increased by 3-4 times.