The main factors limiting the mass production of TiAI-based components are the high reactivity of TiAl- based alloys with the crucible or mould at high temperature. In this work, various crucibles （e.g. CaO, Y203 cer...The main factors limiting the mass production of TiAI-based components are the high reactivity of TiAl- based alloys with the crucible or mould at high temperature. In this work, various crucibles （e.g. CaO, Y203 ceramic crucibles and water-cooled copper crucible） were used to fabricate the Ti-47Al-2Cr-2Nb alloy in a vacuum induction furnace. The effects of crucible materials and melting parameters on the microstructure and mechanical properties of the alloy were analyzed by means of microstructure observation, chemical analysis, tensile test and fracture surface observation. The possibilities of melting TiAI alloys in crucibles made of CaO and Y2O3 refractory materials were also discussed.展开更多
The effect of strain rate and deformation temperature on theα→βphase transformation in 47Zr-45Ti-5Al-3V alloy with an initial widmanstattenαstructure was investigated.At the deformation temperature of 550°C,t...The effect of strain rate and deformation temperature on theα→βphase transformation in 47Zr-45Ti-5Al-3V alloy with an initial widmanstattenαstructure was investigated.At the deformation temperature of 550°C,the volume fraction ofαphase decreased with increasing strain rate.At 600 and 650°C,the volume fraction ofαphase firstly increased to a maximum value with increasing strain rate from 1×10-3 to 1×10-2 s-1,and then decreased.At 700°C,the microstructure consisted of singleβphase.At a given strain rate,the volume fraction ofαphase decreased with increasing deformation temperature.With decreasing strain rate and increasing deformation temperature,the volume fraction and size of globularαphase increased.At 650°C and 1×10-3 s-1,the lamellarαphase was fully globularized.The variation in the volume fraction and morphology ofαphase with strain rate and deformation temperature significantly affected the hardness of 47Zr-45Ti-5Al-3V alloy.展开更多
依据粉末冶金Ti-47Al-2Nb-2Cr合金热模拟压缩实验结果,研究了变形温度为950～1150 ℃、应变速率为0.001～0.1 s(-1)条件下材料的流变力学行为。采用Poliak和Jonas所提出的临界条件动力学理论,确定了该合金的动态再结晶临界应变(ε_c)和...依据粉末冶金Ti-47Al-2Nb-2Cr合金热模拟压缩实验结果,研究了变形温度为950～1150 ℃、应变速率为0.001～0.1 s(-1)条件下材料的流变力学行为。采用Poliak和Jonas所提出的临界条件动力学理论,确定了该合金的动态再结晶临界应变(ε_c)和临界应力(σ_c),揭示了变形温度与应变速率对ε_c和σ_c的影响规律。结果表明,温度补偿应变速率因子Z与ε_c、σ_c、ε_p(峰值应变)和σ_p(峰值应力)间的关系可以采用指数函数形式表征。建立了该合金动态再结晶临界发生模型:ε_c=1.2×10^(-3)Z^(0.147),动态再结晶临界应变与流变应力曲线峰值应变的比值约为 0.73。根据对模型的分析表明,临界应变与 Z 参数之间呈现正相关性,即随着 Z 参数的减小(变形温度升高或应变速率降低),材料发生动态再结晶的临界应变减小,说明变形温度的升高与应变速率的下降能够促进动态再结晶行为的发生。通过对热变形后微观组织的观察,验证了所建立动态再结晶临界模型的可靠性。展开更多
文摘The main factors limiting the mass production of TiAI-based components are the high reactivity of TiAl- based alloys with the crucible or mould at high temperature. In this work, various crucibles （e.g. CaO, Y203 ceramic crucibles and water-cooled copper crucible） were used to fabricate the Ti-47Al-2Cr-2Nb alloy in a vacuum induction furnace. The effects of crucible materials and melting parameters on the microstructure and mechanical properties of the alloy were analyzed by means of microstructure observation, chemical analysis, tensile test and fracture surface observation. The possibilities of melting TiAI alloys in crucibles made of CaO and Y2O3 refractory materials were also discussed.
基金Project(201629) supported by the Scientific Research Foundation for Introduced Talent of Guizhou University,ChinaProjects(20164014,20165654) supported by the Hundred-level Innovative Talents Project of Guizhou Province,ChinaProject(20146013) supported by the Science and Technology of Guizhou Province,China
文摘The effect of strain rate and deformation temperature on theα→βphase transformation in 47Zr-45Ti-5Al-3V alloy with an initial widmanstattenαstructure was investigated.At the deformation temperature of 550°C,the volume fraction ofαphase decreased with increasing strain rate.At 600 and 650°C,the volume fraction ofαphase firstly increased to a maximum value with increasing strain rate from 1×10-3 to 1×10-2 s-1,and then decreased.At 700°C,the microstructure consisted of singleβphase.At a given strain rate,the volume fraction ofαphase decreased with increasing deformation temperature.With decreasing strain rate and increasing deformation temperature,the volume fraction and size of globularαphase increased.At 650°C and 1×10-3 s-1,the lamellarαphase was fully globularized.The variation in the volume fraction and morphology ofαphase with strain rate and deformation temperature significantly affected the hardness of 47Zr-45Ti-5Al-3V alloy.
文摘依据粉末冶金Ti-47Al-2Nb-2Cr合金热模拟压缩实验结果,研究了变形温度为950～1150 ℃、应变速率为0.001～0.1 s(-1)条件下材料的流变力学行为。采用Poliak和Jonas所提出的临界条件动力学理论,确定了该合金的动态再结晶临界应变(ε_c)和临界应力(σ_c),揭示了变形温度与应变速率对ε_c和σ_c的影响规律。结果表明,温度补偿应变速率因子Z与ε_c、σ_c、ε_p(峰值应变)和σ_p(峰值应力)间的关系可以采用指数函数形式表征。建立了该合金动态再结晶临界发生模型:ε_c=1.2×10^(-3)Z^(0.147),动态再结晶临界应变与流变应力曲线峰值应变的比值约为 0.73。根据对模型的分析表明,临界应变与 Z 参数之间呈现正相关性,即随着 Z 参数的减小(变形温度升高或应变速率降低),材料发生动态再结晶的临界应变减小,说明变形温度的升高与应变速率的下降能够促进动态再结晶行为的发生。通过对热变形后微观组织的观察,验证了所建立动态再结晶临界模型的可靠性。
