【摘要】 通过Gleeble-3500热模拟试验机在950～1150℃,应变速率为0.01～3s^-1条件下的近等温热模拟压缩实验,建立了NiPt15合金的流变应力-应变曲线及其热加工图。分析了NiPt15合金不同变形阶段的功率耗散情况;阐明了NiPt15合金的损伤失稳机制;基于Prasad动态材料模型获得了不同应变速率、温度条件下的能量耗散率和失稳系数;研究了应变量、温度和应变速率对于能量耗散率和失稳系数的影响。结果表明:（1）变形温度是影响曲线变化趋势及动态再结晶的主要因素,且变形温度越高,应变速率越低,动态再结晶越充分;（2）加工失稳机制主要包括局部塑性变形、剪切变形带以及开裂,随真应变的增大先发生局部塑性变形,而后由剪切变形带取代,并最终向开裂演变;（3） NiPt15合金较为优异的加工实验条件主要集中在非失稳区,即变形参数1000～1100℃,0.03～0.1 s^-1以及1100～1130℃,0.01～0.03 s^-1范围内,并通过显微组织分析对热加工图进行了验证。更多还原

【Abstract】 Based on the isothermal compression tests of NiPt15 alloys at temperature ranging from 950 ℃ to 1150 ℃ and strain rate from 0.01 s^-1 to 3 s^-1 performed on Gleeble-3500 thermo-simulation machine, the stress-strain relationship curve and hot processing maps of NiPt15 during the hot deformation process were established. The power dissipation situation of NiPt15 alloy at different stages was analyzed. The damage instability mechanism of NiPt15 alloy was elucidated. According to the dynamic material model presented by Prasad, the power dissipation rate and instability coefficient were obtained under different strain rates and temperature. And then the effects of strain, temperature and strain rates on power dissipation rate and instability coefficient were investigated. The results show that the deformation temperature is the main factor affecting the curve variation trend and dynamic recrystallization. Moreover, the higher the deformation temperature is and the lower the strain is rate, the more sufficient the dynamic recrystallization will the. Subsequently, the instability mechanism of NiPt15 alloy in thermal processing mainly includes local plastic deformation, shear deformation zone and cracking. With the increase of true strain, local plastic deformation occurs firstly,then shear deformation zone replaces it, and finally it evolves into cracking. The excellent safe processing zone for NiPt15 alloy is mainly concentrated in the non-instability zone. That is to say, the deformation parameters are within the range of 1000～1100 ℃, 0.03～0.1 s^-1 and 1100～1130 ℃, 0.01～0.03 s^-1. Moreover, the thermal processing map was verified by microstructure analysis.更多还原