采用热模拟系统研究了半固态变形温度,应变速率和变形量对Ti14合金压缩行为和组织演变的影响.结果表明:温度和应变对Ti14合金半固态峰值应力影响较大,峰值应力随着温度的增加和应变速率的减小而降低.分析认为:半固态变形中,应变速率的变化会影响产生压缩变形所需的响应时间,而液相的含量受控于变形温度,随着变形温度的升高,组织中出现了网状晶界结构,使得变形机制由固相粒子的塑性变形转变为固液混合流动.此外,变形量对合金半固态变形的应力-应变影响较小,可以认为是液相的润滑作用和协调变形机制缓解了晶粒间的压缩应力和摩擦力,使得应力-应变变化不明显.
The effects of the processing parameters on the deformation behavior of Ti14 alloy containing a small volume of liquid have been investigated through compressive tests.Experiments were conducted at deformation temperatures from 1000 to 1150 ℃,strain rates from 5× 10-3 to 5 s-1 and deformation degrees from 40％ to 70％.The results show that deformation temperature and strain rate have significant effects on the peak flow stress.The flow stress decreases with increasing of deformation temperature and/or decreasing of strain rate.The response time required by deformation is affected by the strain rate and liquid fraction is controlled by the temperature.As the temperature increases,deformation mechanism transforms from sliding between solid particles (SS) to the flow of liquid incorporating solid particles (FLS),which improves the semi-solid deformation behavior.In addition,the flow stress decreases with increasing of deformation degrees during the compression which is associated with lubricating effect of liquid during semi-solid deformation.
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