热挤压和时效处理对生物可降解Mg-Zn-Y合金性能的影响

The influence of hot extrusion and age treatment on the properties of biodegradable Mg-Zn-Y alloy

摘要:

本研究采用粉末冶金法制备了Mg-6%Zn-1%Y生物医用镁合金并进行了热挤压变形处理。挤压后的样品在150°C下分别时效24h和72h。对实验用合金的显微组织和腐蚀行为进行了研究。显微组织结果表明，合金包含α-Mg, MgZn, MgZn2和Mg3YZn6（I相）。热挤压工艺显著细化晶粒并提高了合金的力学性能和耐腐蚀性能。其中热挤压后合金的压缩强度在365~399MPa之间，且浸泡实验中的析氢量低于烧结态合金。另外，由于更均匀的腐蚀行为，时效72h的合金分别在浸泡实验和动电位极化实验中显示出更低的腐蚀速率和腐蚀电流密度，并在电化学阻抗谱(EIS)中获得了较高的电阻值(Rp)，结果表明，时效72h合金较其他3种合金具有更优异的腐蚀性能。

Abstract:

Mg-6Zn-1Y (mass fraction, %) alloys were prepared for degradable biomaterials. The billets of the alloy were produced by powder metallurgy (PM) method and then hot extruded. The extruded samples were aged for 24h and 72h at 150°C respectively. The microstructure and corrosion behavior of the experimental alloys were comprehensively investigated. The microstructure observations show that the alloys contain α-Mg, MgZn, MgZn₂ and Mg₃YZn₆ (I-phase) phases. The hot extrusion process significantly refined the grains and led to better mechanical properties with the value of compressive strength in the range of 365~399MPa, and better corrosion resistance for the PM alloy shows higher hydrogen volume in the immersion test. Furthermore, due to more uniform corrosion behavior, the alloy aged for 72h shows lower corrosion rate and corrosion current density in the immersion test and potentiodynamic polarization test respectively, and higher resistance value (R_p) results from the electrochemical impedance spectroscopy (EIS), which means the alloy aged for 72h exhibits better corrosion resistance than the other three alloys.