摘要
采用差热分析方法(DTA)和熔体超温处理技术,研究熔体过热温度对一种第三代镍基单晶高温合金凝固特性及组织的影响。结果表明:当熔体过热温度从1450℃提高到1500℃时,形核过冷度与结晶温度间隔变化不明显,γ相在一个较宽的温度范围内形核生长;而当熔体过热到1580℃时,形核过冷度急剧增大,结晶温度间隔显著减小,γ相形核生长温度范围减小,γ/γ′共晶组织析出减少,γ′相的析出温度较熔体过热到1450℃条件下升高了9℃;当熔体过热温度进一步升高到1650℃时,形核过冷度略有减小,结晶温度间隔稍有增大。当熔体超温处理温度由1500℃提高到1580℃时,枝晶组织明显细化,而进一步提高熔体超温处理温度至1650℃时,枝晶组织反而略有粗化。熔体过热温度使熔体结构发生改变,从而对合金的凝固特性及组织产生影响。
The effect of the melt overheating temperature on solidification characteristics and microstructure of a third generation Ni-based single crystal superalloy was studied by the Differencial Thermal Analysis （DTA） and the melt superheating treatment. The results show that as the melt overheating temperature increases from 1450 to 1500 °C, the nucleation supercooling and solidification interval change a little, the nucleation and growth of γ phase are in a wide range of temperature. When the melt overheating temperature is above 1580 °C, the nucleation supercooling increases sharply and the solidification interval decreases obviously. At the same time, the temperature range of nucleation and growth of γ phase is reduced, the precipitation of γ/γ′ eutectic is decreased, and the precipitation temperature of γ′ phase is elevated by 9 °C compared with the one overheated to 1450 °C. When the melt overheating temperature rises to 1650 °C, the nucleation supercooling decreases, and the solidification interval increases appreciably. As the melt superheating temperature increases from 1500 to 1580 °C, the dendrite structure is refined significantly, but then coarsened slightly when the melt superheating temperature rises to 1650 °C. The results are primarily attributed to the melt structure change caused by the melt overheating temperature, and the solidification characteristics and microstructure of alloy are affected finally.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2013年第5期1028-1032,共5页
Rare Metal Materials and Engineering
基金
国家"973"项目(2010CB631202
2011CB610406)
国家自然科学基金(50931004
51101120)
关键词
镍基单晶高温合金
差热分析(DTA)
熔体过热温度
凝固特性
凝固组织
Ni-based single crystal superalloy
differencial thermal analysis （DTA）
melt overheating temperature
solidification characteristics
solidification microstructure
