AZ31镁合金板微动磨损性能和微观组织演变的各向异性

Anisotropy of fretting wear performace and microstructure evolution of AZ31 Mg alloy plate

AZ31轧制镁合金是最具前景的接骨板材料之一,晶体织构对微动磨损行为及微观组织演变的影响规律尚不明确。采用球/平面接触方式在AZ31镁合金板材的不同平面开展不同滑移方向的切向微动磨损试验,利用光学显微镜、电子扫描电镜、白光干涉仪、电子背散射衍射对磨斑的微观形貌和磨损体积进行了系统表征,对比不同微动磨损状态下的磨损性能和磨损机制。结果表明:载荷沿法向ND、微动沿切向TD(ND-TD)的抗磨损性能最优,载荷沿切向TD、微动沿轧向RD(TD-RD)的抗磨损性能次之,载荷沿切向TD、微动沿法向ND(TD-ND)的抗磨损性能最差。三种工况下材料的主要磨损机制均为磨粒磨损,磨斑周边和次表层的微观组织发生演变,尤其是{1012}〈1120〉拉伸孪晶的产生与晶粒所受到的应力及其晶体取向有关,从而导致材料的微动磨损性能呈现各向异性。

Rolled AZ31 magnesium alloy is one of the most promising bone plate materials,but the influence of crystal texture on fretting wear behavior and the microstructure evolution are not yet clear.The fretting wear tests along different directions were carried out in different planes of AZ31 magnesium alloy with a ball-on-flat contact configuration.The morphology and wear volume of the worn surfaces under different fretting wear cases were characterized using optical microscope(OM),scanning electron microscope(SEM),white light interferometer(WLI)and electron backscatter diffraction(EBSD).And the wear properties and wear mechanism of different cases were analyzed and compared.The results show that the load is carried along the normal direction ND and the fretting is carried along the tangential direction TD(ND-TD),the anti-wear performance is best.The load is carried along the tangential direction TD and the fretting direction is carried along rolling direction RD(TD-RD),the anti-wear performance is the second.When the load is carried along the tangential direction TD and the fretting direction is carried along normal direction ND(TD-ND),the anti-wear performance is the worst.The main wear mechanism is abrasive wear.The microstructure of the zones around and beneath the worn scar,especially{1012}〈1120〉twin,exhibits anisotropy and is closely related to the stress and crystal orientation of the grains,which directly influence their fretting wear performance.