试样截面尺寸变化对高温合金DZ125定向凝固组织的影响.pdfVIP

学兔兔 Jun．2o09 铸 造 FOUNDRY ·589· VOI．58 NO．6 试样截面尺寸变化对高温合金DZ1 25 定向凝固组织的影响 陈 波，刘 林，张卫国，傅恒志 (西北工业大学凝固技术国家重点实验室，陕西西安710072) 摘要：采用截面变化的DZI25高温合金试样进行液态金属冷却定向凝固，抽拉速率为25 i~m／s、50t~rn／s、100i~m／s和 500 p~m／s。获得了截面变化前后的稳定组织以及截面变化区的组织演变。结果表明，当凝固顺序由大截面向小截面时。 一 次枝晶间距变窄，抽拉速率为500 时，枝晶生长方向发生偏转。随着试样比表面积的增大，一次枝晶间距减小。 由于截面的变化，组织的演化是一个渐变的过程，不同的冷却速率和凝固顺序都影响着组织的演化过程。 关键词：高温合金；定向凝固；截面尺寸变化；抽拉速率 中图分类号：TG146．1+5 文献标识码：A 文章编号：1001--4977(2009)06—0589—04 Effect Of Variation in Cross．Section Size of Sam ples On DirectionaI Solidification Microstructure Of DZ1 25 Superalloy CHEN Bo。LIU Lin，ZHANG Wei—guo，FU Heng-zhj (State Key Laboratory of Solidification Processing，Northwestern Polytechnical University， XI．an 71 0072。Shaanxi。China) Abstract：With directionaI solidification of liquid metaI cooling。the stable microstructure of the samples with different size of the cross section and the microstructure evolution of section—changed region were obtained at the withdrawaI rate of 25 iJm／s，50 pm／s，1 O0 Um，s and 500 pm／s，respectively f0r the DZ1 25 superalloy．It iS concluded that the primary dendrite arm spacing(PDAS)narrows down with the CROSS．section size decrease．The deflection of dendrite growth direction Occurs at the rate of 500 iJm／s．With the jncrease of specific surface area of the samples，the PDAS reduces．Due to the variation in cross．section size．the evolution of microstructure gradually OCCU~．Both cooling rate and solidification sequence impact on structure evolution process． Key words：superal