MB15镁合金半固态压缩力学行为研究

通过MB15镁合金半固态等温压缩试验，研究了半固态材料的力学行为，提出了触变强度是半固态金属在稳态变形过程中触变点的应力，即半固态金属固体骨架所能承受的最大正应力，并分析了加热温度、应变速率、保温时间、固相晶粒大小、晶粒圆整度及材料本身的强度等因素对半固态触变强度的影响，提出了触变强度的存在条件。结果表明，半固态触变强度随着加热温度的升高、应变速率的降低及保温时间的延长而降低，随着固相晶粒的减小、晶粒圆整度的增加及材料本身强度的增加而增加；当半固态材料内部的固相颗粒相互连结形成固体骨架时，存在触变强度。

Mechanical Behavior of Semi-solid MB15 Magnesium Alloy during Steady Compression

The mechanical behavior of semi-solid MB15 magnesium alloy was investigated based on an isothermal compression experiment. The concept of thixotropic strength that is the maximum stress borne on the solid skeleton of semi-solid materials is put forward, which is the stress corresponding to the thixotropic point during steady deformation. Effects of some factors, including the heating temperature, strain rate, holding time, solid grain size, grain roundness as well as the intrinsic strength of the materials, on the thixotropic strength were analyzed, and existent conditions of the thixotropic strength was given. The results show that thixotropic strength is decreased with increase the heating temperature, decreasing the strain rate and extending the holding time while is increased with lowering the solid grain size, increasing the grain roundness and intrinsic strength of the material. The thixotropic strength exists when the solid grain in semi-solid materials jointed with each other to constitute the solid skeletons.