摘要
分别采用热力学计算(thermo-calc,TC),差热分析(differential thermal analysis,DTA)和金相法(metallography observation)测定一种新型镍基粉末高温合金(CSU-A)的铸态母合金及其热挤压态合金的相变温度,分析和对比升温测试和降温测试对差热分析结果的影响。结果表明,热力学计算可准确预测合金的固、液相线温度;铸态合金的γ′相先后发生2次析出/固溶,且γ′相的完全固溶温度高于挤压态合金的γ′相完全固溶的温度;DTA降温曲线的相变温度低于升温曲线的相变温度,凝固过冷度(TL)和γ′相析出过冷度(T1γ′,T2γ′)分别为16,35和43℃。最终确定挤压态CSU-A合金的γ′相完全固溶温度为1 145±5℃,铸态合金的γ′相完全固溶温度为1 196℃,固、液相线温度分别为1 25 9和1 356℃。
The phase transformation temperatures of as-cast and hot extruded nickel-based superalloy were determined accurately by thermodynamic calculation （TC）, differential thermal analysis （DTA） and metallography observation. The effects of increasing and decreasing temperature tests on DTA results were analyzed and compared separately. The results show that, thermodynamic calculation by TC can accurately predict the solidus and liquidus temperatures. The γ′ phase of as-cast alloy has precipitated twice from the matrix. The complete solution temperature of γ′ phase is higher than that of hot extruded alloy. The phase transformation temperatures gotten from the decreasing temperature curve is lower than that of the increasing temperature curve in the DTA test. The degree of superseding for solidification （TL） and precipitation of γ′ phase （T1γ′, T2γ′） are 16 ℃, 35 ℃ and 43 ℃, respectively. The γ′ phase transformation temperatures of extruded and as-cast alloy are determined to be 1 145±5 ℃ and 1 196 ℃ （DTA）, respectively. The solidus and liquidus temperatures are determined to be 1 259 ℃ and 1 356 ℃, respectively.
出处
《粉末冶金材料科学与工程》
北大核心
2017年第6期719-726,共8页
Materials Science and Engineering of Powder Metallurgy
基金
国家高技术研究发展计划资助项目(2012AA03A514)
国家重点研发计划资助项目(2016YFB0700300)
关键词
粉末高温合金
相变温度
热力学计算
差热分析
金相法
powder metallurgy superalloy
phase transformation temperature
thermodynamic calculation
DTA
metallography observation
