Mg-6Gd-2Zn-0.4Zr镁合金的组织与摩擦磨损性能

Microstructure,friction and wear resistance of Mg-6Gd-2Zn-0.4Zr alloy

用扫描电镜、硬度计及摩擦磨损试验机研究了不同状态Mg-6Gd-2Zn-0.4Zr（GZ62K）镁合金的显微组织、硬度和摩擦磨损性能。结果表明：铸态镁合金晶界处有白亮色β-（Mg,Zn）3Gd相,晶界周围有片层状LPSO结构;T4和T6处理后,β相减少,LPSO结构消失;挤压加工后,镁合金晶粒细化,晶粒内部重新形成了LPSO结构。4种状态的镁合金硬度差别不大。不同状态镁合金的磨损机制都有磨粒磨损,铸态和T4态合金中存在粘着磨损;挤压加工后存在氧化磨损,其中挤压态镁合金耐磨性最好。LPSO结构、位错和晶界的相互交割以及β相对晶界的钉扎有利于提高镁合金的耐磨性能。

Microstructure,hardness,friction and wear resistance of Mg-6Gd-2Zn-0.4Zr（GZ62K）alloy were studied by using scanning electron microscope,hardness tester and friction and wear tester.The results show that the brightβ-（Mg,Zn）3Gd phase distributes at the grain boundary and the lamellar LPSO structure locates around the grain boundary in the as-cast magnesium alloy.Theβphase reduces and the LPSO structure disappears after T4 and T6 treatment.After extrusion processing,the grain of magnesium alloy refines and the LPSO structure reforms in grains.The microhardness of the four magnesium alloys is similar.Different treatment of the alloys all show abrasive wear mechanism.The as-cast and T4 treatment alloys also show adhesive wear mechanism,but it becomes oxidation wear after extrusion processing.The wear resistance of alloy after extrusion processing is the best.In general,the pinning effect ofβphase and the intersection of LPSO structure,dislocation and grain boundary are beneficial to improving the wear resistance of magnesium alloy.