高应变速率下55%TiB_2颗粒增强铝基复合材料绝热剪切带的组织特征

Microstructure Characteristic of Adiabatic Shear Band in 55vol% TiB_2 Particles Reinforced Aluminum Matrix Composite at High Strain Rates

为研究铝基复合材料中新发现的以熔化为主要特征的相变带,采用分离式霍普金森压杆(SHPB)和光学显微镜(OM)、扫描电镜(SEM)等研究了不同应变速率(7×10-4~2×103 s-1)下55%TiB2颗粒增强铝基复合材料中绝热剪切带的组织特征。结果表明:在(1~2)×103 s-1的高应变速率下,在与加载方向呈45°的剪切面上存在熔融铝带或熔融铝球团聚区,即相变带;相变带的形成与绝热温升有关,在绝热温升的作用下基体合金于高温下熔化,急冷后形成了相变带;试验用铝基复合材料的绝热剪切失效主要受热软化效应的控制。

In order to research the new-found phase transformation band with the main characteristic of melting in aluminum matrix composite, microstructure characteristics of adiabatic shear band in 55vol% TiB2 particles reiforced aluminum matrix composite at varied strain rates （7× 10-4 -2 ×10^3 s^-1 ） were researched by using split Hopkinson pressure bar （SHPB）, optical microscope （OM） and scanning electron microscope （SEM）. The results show that molten aluminum bands or accumulation area of molten aluminum cells at approximate 45° to the compression axis, which was called phase transformation band, were found on the shear plane at high strain rates of （1-2）×10^3 s^-1. The formation of phase transformation band was related with adiabatic temperature-rise, which caused the aluminum alloy matrix melting, after quick cooling, the phase transformation formed. Adiabatic shear failure for the experimental aluminum matrix composite was controlled by thermal softening effect.