超声处理对Mg-3Al-1Sb合金凝固组织与力学性能的影响行为与机理研究

Investigation on the Effect Behavior and Mechanism of Ultrasonic Treatment on the Solidification Microstructure and Mechanical Properties of Mg-3Al-1Sb Alloy

铸态Mg-Al系合金晶粒粗大且使用温度较低,可通过添加Sb元素形成高熔点的Mg_(3)Sb_(2)相来提高Mg-Al合金的使用温度。但常规凝固组织中的Mg_(3)Sb_(2)相尺寸较大,呈不规则状分布,且Sb元素在Mg-Al合金中易偏析,对合金的性能不利。通过在Mg-3Al-1Sb合金的凝固阶段进行超声处理,研究了超声处理对合金凝固组织和力学性能的影响,特别是对Mg_(3)Sb_(2)相的细化作用。研究结果表明:超声处理可有效地细化Mg_(3)Sb_(2)相,使Mg_(3)Sb_(2)相的形貌由粗大的针棒状转变为细小的块状;同时,超声处理可有效地细化合金基体晶粒尺寸、提高合金的力学性能。最后,讨论了超声处理对Mg-Al合金组织改善的作用机制,并提出了超声对Mg-Al合金熔体作用机制的微观模型。

The most widely used as-cast Mg-Al alloy has coarse grain size and possess low operating temperature.The addition of Sb element can form Mg_(3)Sb_(2)phase with high melting point to improve the operating temperature of Mg-Al alloy.However,the Mg_(3)Sb_(2)in the conventional microstructure of Mg-Al alloy is large in size and irregular in shape and distribution,and the element Sb is easy to segregate in solidification,which has a negative performance of the alloy.In this paper,ultrasonic treatment(UT)was carried out in the solidification stage of Mg-3Al-1Sb alloy,and the influence of UT on the solidification structure of the alloy,special for the refining role of Mg_(3)Sb_(2)phase was studied.The investigation results show that the UT can effectively refine Mg_(3)Sb_(2)phase,change the morphology of Mg_(3)Sb_(2)phase from thick needle into small lumps.At the same time,UT also can refine the matrix grain size and improve mechanical properties of the alloy.Finally,the mechanism of UT on the improvement of solidification microstructure were discussed,and an novel micro-model of UT was proposed.