合金化元素Sn对镁合金组织与性能影响的研究进展

Research progress in effects of alloying element Sn on microstructures and properties of Mg alloys

纯镁具有密度低、减震性能好、生物相容性好等优点,但是强度低。合金化是调控纯镁组织和性能的重要方法。Sn具有熔点低、与Mg的共晶温度高、在Mg中的固溶度大、化学性质稳定和产量大等特点,适合作为合金化元素。本文综述了合金化元素Sn对镁合金组织与性能的影响,由于Sn元素在固/液界面前沿富集、固溶后降低镁基体锥面与基面位错滑移临界分切应力的比值、固溶后提高基体电位、形成Mg_(2)Sn析出相后阻碍位错和晶界运动、与镁基体构成腐蚀原电池等,可产生晶粒细化、时效硬化和强化、提高塑性、调控腐蚀速率、提高放电效率和放电电位等作用。目前制约Mg-Sn基合金发展的主要问题是时效缓慢、硬度和强度低。未来应发展快速显著时效强化的Mg-Sn基合金、含Sn的高塑性变形镁合金和含Sn的结构-功能镁合金。

Pure Mg has advantages of low density,good shock absorption performance and good biocompatibility,but its strength is low.Alloying is an important method to modify microstructure and properties of pure Mg.Sn has characteristics of low melting point,high eutectic temperature with Mg,high solid solubility in Mg,stable chemical properties and large output,which is appropriate to be an alloying element.The effects of alloying element Sn on microstructures and properties of Mg alloys were reviewed in this paper.Sn enriches at the front of the solid-liquid interface,dissolves in Mg matrix,reduces the ratio of critical resolved shear stress value of the pyramidal plane to that of the basal plane,and elevates the electric potential of Mg matrix.Mg_(2)Sn precipitates can hinder dislocation and grain boundary movement,and form galvanic corrosion cells with Mg matrix.Therefore,effects of Sn addition include grain refinement,age hardening and strengthening,improving plasticity,accelerating or reducing corrosion rate,enhancing discharge efficiency and discharge potential.At present,the main problems restricting the development of Mg-Sn alloys are slow aging,low hardness and strength.In the future,endeavors should be made to develop rapidly age-hardenable Mg-Sn alloys with high strengths,wrought Sn-containing Mg alloys with good ductility,and Sn-containing structural-functional Mg alloys.