热挤压对AM50-1%Gd合金组织与性能的影响

Influence of hot extrusion on microstructure and properties of AM50-1%Gd alloy

针对镁合金高温力学性能差的问题,通过采用热挤压、时效处理、力学性能测试及组织形貌观察等方法,研究了热挤压处理对AM50-1%Gd合金组织与性能的影响.结果表明:AM50-1%Gd合金组织结构由α-Mg、Mg17A l12和Mg2Gd相组成.热挤压可明显提高AM50-1%Gd合金的抗拉强度和屈服强度,并随着挤压温度的降低,合金的强度值增大.而经时效处理后,挤压态合金在室温及高温的抗拉强度和屈服强度可再次提高.挤压态AM50-1%Gd合金中的细小晶粒来自于热挤压期间发生的动态再结晶,热挤压能提高合金抗拉强度的主要原因是形变强化和细晶强化,而细晶强化和细小第二相沿晶界弥散析出是时效态合金综合力学性能好的主要原因.

Aimed at improving the mechanical properties of magnesium alloy at high temperature, the effect of hot extrusion on the rnicrostructnre and mechanical properties of the AM50-1% Gd alloy was investigated through the measurement of mechanical properties and observation of microstructure. The results show that the microstructnre of the AM50-1% Gd alloy consists of ct-Mg matrix, Mg^TAlj2 and Mg2Gd phases. The ultimate tensile strength （ UTS ） and yield tensile strength （YTS） of the alloy are obviously enhanced by hot extrusion. And the strength of the alloy is increased with reducing the extruding temperature. Furthermore, both UTS and YTS of the extruded AM50-1% Gd alloy at room and high temperatures are enhanced again by means of aging treatment. The finer grains in the extruded AM50-1% Gd alloy result from the dynamic recrystallization occurred during hot extrusion. For as-extruded AM50-1% Gd alloy, the improvement in the UTS of the alloy can mainly be attributed to the refining and deforming strengthening. And the refining strengthening and the precipitation of the finer second phases along the grain boundary are the main reason why the aged alloy possesses the better synthetic mechanical properties.