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采用放电等离子烧结法(SPS)制备出30%Cr-Cu复合材料,对其致密度、硬度和导电率等相关性能进行测试,并观察分析该复合材料的显微组织。利用Gleeble-1500D型热模拟试验机在变形温度650~950℃、应变速率0.001~10s-1、变形量60%的条件下对30%Cr-Cu复合材料进行热模拟压缩试验。对热压缩试验得到的真应力-应变数据进行拟合、计算和分析,构建该复合材料的本构方程,同时得到材料的加工硬化率θ,利用材料的lnθ-ε曲线出现有拐点和-(lnθ)/ε-ε曲线对应有最小值这一判据,分析该复合材料的动态再结晶临界条件。结果表明:30%Cr-Cu复合材料的真应力-应变曲线主要以动态再结晶软化机制为特征,峰值应力随应变速率的增加和温度的降低而升高;该复合材料的lnθ-ε曲线出现拐点,-(lnθ)/ε-ε曲线对应有最小值,该最小值所对应的应变为临界应变εc,且εc随变形温度的升高和应变速率降低而减小,εc与Zener-Hollomon参数Z的函数关系为εc=2.38×10-3 Z0.1396。
The 30% Cr-Cu composites were prepared by spark plasma sintering (SPS), and their properties of density, hardness and electrical conductivity were tested. The microstructure of the composites was observed and analyzed. The thermal simulation of 30% Cr-Cu composites was carried out by using the Gleeble-1500D thermal simulation machine under the conditions of deformation temperature of 650-950 ℃, strain rate of 0.001-10s-1 and deformation of 60%. The true stress-strain data obtained from the hot compression test are fitted, calculated and analyzed. The constitutive equation of the composite material is constructed and the work hardening rate θ of the material is obtained. The inflection points and - (lnθ) / ε-ε curve corresponding to the minimum corresponding to the criterion, the dynamic recrystallization critical conditions of the composite materials. The results show that the true stress-strain curve of 30% Cr-Cu composites is mainly characterized by the dynamic recrystallization softening mechanism. The peak stress increases with the increase of strain rate and the decrease of temperature. The lnθ-ε curve of the composites At the inflection point, there is a minimum value corresponding to the curve of - (lnθ) / ε-ε. The minimum corresponds to the critical strain εc, and εc decreases with the increase of deformation temperature and strain rate. Εc and Zener- Hollomon parameter Z as a function of εc = 2.38 × 10-3 Z0.1396.