TiBw/TA15复合材料板材超塑变形行为研究

研究了TiB_w/TA15复合材料板材在900~960℃、5×10^-4~10^-2s^-1条件下的超塑变形行为。结果表明,TiB_w/TA15复合材料流变应力随拉伸温度的升高和应变速率的减小而降低,在940℃、5×10^-3s^-1变形条件下获得的最大超塑性伸长率为439%。利用Zener-Hollomn参数和Arrhenius方程所建立的峰值应力本构方程为ε·=3.55×10⁸sinh(2.0×10^-2σ)]^1.99×exp(-6.381×10⁵/RT),其变形激活能Q=638.1kJ/mol。复合材料超塑性变形组织与拉伸温度和应变速率密切相关。高温低应变速率有利于基体α相的动态再结晶以及晶须与基体处孔洞的愈合,低温高应变速率下,孔洞更易萌生于增强相与基体结合界面的端部。动态再结晶对复合材料超塑性的发挥起着关键作用。

Superplastic Deformation Behavior of TiBw/TA15 Composite Sheet

Superplasticity of TiB_w/TA15 composite sheet under the conditions of 900-960℃and 5×10^-4-10^-2s^-1was studied.The results showed the flow stress of TiB_w/TA15 composite decreases with the deformation temperature increasing and strain rate decreasing,and the strain softening characteristics are significant under the condition of low temperature and high strain.The maximum elongation obtained at 940℃and 5×10^-3s^-1was 439%.A constitutive equation based on the Zener-Hollomn parameter and Arrhenius equation wasε·=3.55×10⁸sinh(2.0×10^-2σ)]^1.99×exp(-6.381×10⁵/RT)for TiB_w/TA15 composite,and the deformation energy Q=638.1kJ/mol.The superplastic deformation structure of composite materials is closely related to the tensile temperature and strain rate.The high temperature and low strain rate are beneficial to the dynamic recrystallization of the matrixαphase and the healing of the whiskers and the holes in the matrix.The change of grain size contributes more to superplasticity than the effect of voids on superplastic elongation.The low temperature and high strain rate are beneficial to the holes healing at the end of the interface between reinforced phase and matrix.Dynamic recrystallization plays a key role in superplasticity of composites.