凝固参数对DZ125合金叶片类铸件微观组织和性能的影响  

Influence of Solidification Parameters on the Microstructure and Properties of DZ125 Superalloy Castings

作　　者：葛丙明[1] 刘林[1] 张军[1] 傅恒志[1] 汤鑫[2] 曹腊梅[2] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072 [2]北京航空材料研究院,北京100095

出　　处：《稀有金属材料与工程》2012年第5期840-846,共7页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(50931004);国家重点基础研究发展计划项目(2006CB605202;2010CB631202);国家高技术研究发展计划项目(2007AA03Z552)

摘　　要：应用高速凝固定向凝固方法研究凝固工艺参数(抽拉速度、模壳保温温度)对DZ125高温合金铸件组织及性能的影响。结果发现,升高模壳保温温度可大幅度提高温度梯度,并制备出晶粒挺直度更为优良的铸件。枝晶组织及γ′析出相在壁厚较大部位更为粗大,且均随着抽拉速率及模壳保温温度的提高得到细化。显微偏析随抽拉速率的增加先减轻后加重,随模壳保温温度的提高部分元素偏析加重,部分元素减轻;γ+γ'共晶含量随抽拉速率的增大和模壳保温温度的提高而减少。铸件经标准热处理后,枝晶组织模糊不清,γ'析出相由于凝固参数变化而引起的差异显著减轻,且共晶组织几乎全部消除。抽拉速率变化对热处理态铸件性能无显著影响,但温度梯度的提高改善了铸件晶粒的挺直度,减小了晶粒偏离轴向的角度,提高了铸件性能。In this paper,the influences of withdrawal rates and mold heater zone temperature on the microstructures and the properties of heat treated castings were investigated.Results show that a better aligned grain structure and a much higher thermal gradient can be obtained in castings prepared by 'high superheat' technique.Moreover,with elevating of withdrawal rates and mold heater zone temperature,the dendrite structures and size of γ' phase are refined;dendrite structures and size of γ' phase are larger in thicker zone.With the increase of withdrawal rates,γ+γ' eutectic fractions decreases but the micro-segregation decreases initially and then increases.With elevating of heating zone temperature,the γ+γ' eutectic fraction reduces and micro-segregation becomes severe except Ta.After heat treated,the dendrite structures of the castings become ambiguous and the γ' phase prepared with various solidification parameters have no obvious difference.The properties of castings prepared with different withdrawal rates are almost the same,but that prepared with high thermal gradient has a better high temperature rupture life.

关 键 词：镍基高温合金 定向凝固 抽拉速率 过热作用 显微偏析 性能 

分 类 号：TG29[金属学及工艺—铸造]