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在变形温度为250~400℃,应变速率5×10-5~0.5 s~(-1)范围内,研究了均匀化热处理态Mg_2B_2O_5/AZ63B镁基复合材料的热压缩变形行为,并利用双曲线正弦函数建立了其本构方程。结果表明:复合材料的峰值应力及其对应的应变均随温度的降低及应变速率的增加而增大;计算峰值应力与实验值的比较表明双曲正弦函数可以准确描述复合材料的本构关系;复合材料的应力指数n和激活能Q分别为5.5和221 kJ/mol,其变形机制为晶格扩散控制的位错攀移机制。热挤压试验表明:经过均匀化热处理,复合材料的最大及稳态挤压力与铸态相比分别下降了92 kN和80 kN。
The hot compression deformation behaviors of Mg_2B_2O_5 / AZ63B magnesium matrix composites homogenized at 250 ℃ to 400 ℃ and strain rates ranging from 5 × 10-5 to 0.5 s ~ (-1) were investigated. By using hyperbolic curves The sine function establishes its constitutive equation. The results show that both the peak stress and the corresponding strain increase with the decrease of the temperature and the strain rate. Comparing the calculated peak stress with the experimental results shows that the hyperbolic sine function can accurately describe the constitutive relationship of the composites. The stress exponent n and activation energy Q of the composites are 5.5 and 221 kJ / mol, respectively. The deformation mechanism is the dislocation climbing mechanism controlled by lattice diffusion. Hot extrusion tests showed that the maximum and steady-state extrusion pressures of the composites decreased by 92 kN and 80 kN, respectively, compared with the as-cast ones.