K439B镍基铸造高温合金800℃长期时效过程中碳化物的演变规律  

Evolution of Carbides in K439B Nickel-based Cast Superalloy During Long-term Aging at 800℃

作　　者：高磊 屈星海 吴一栋 陈晶阳 肖程波 惠希东[1] GAO Lei;QU Xinghai;WU Yidong;CHEN Jingyang;XIAO Chengbo;HUI Xidong(State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China;Science and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]中国航发北京航空材料研究院先进高温结构材料重点实验室,北京100095

出　　处：《材料导报》2024年第15期8-12,共5页Materials Reports

基　　金：国家科技重大专项项目(J2019-Ⅵ-0004-0117);先进高温结构材料重点实验室基金项目(6142903220101);国家重点研发计划项目(2022YFB3706804)。

摘　　要：K439B镍基合金是一种承温能力达800℃的新型铸造高温材料,在发动机机匣类复杂结构件有重要应用前景。作为该合金中的主要晶界强化相,碳化物在合金长期时效过程中的演化规律尚不清楚。以K439B合金为对象,在800℃下对该合金进行了6000~10000 h的等温时效实验,研究了其长期时效过程中碳化物的演变规律和转变机理。结果表明,K439B合金的组织稳定性优异。经过长期时效后,晶界和枝晶间组织中仍保留大部分标准热处理态时的MC型碳化物,仅有部分MC型碳化物分解为M_(23)C_(6)型碳化物和γ′相,未出现η相和σ相等TCP有害相。晶界M_(23)C_(6)型碳化物表现出两种不同的粗化行为,一是M_(23)C_(6)型碳化物逐渐宽化,在长期时效后宽度均一,碳化物排列整齐;二是在某些晶界部位,粗化后的M_(23)C_(6)型碳化物呈现不规则的形状,甚至向晶粒内部延伸。晶界M_(23)C_(6)型碳化物并未出现沿整个晶界的完全相连情况,其主要是γ′相颗粒将两个相邻的M_(23)C_(6)型碳化物分隔所致。K439B nickel-based superalloy is a new type of cast high-temperature material with a temperature bearing capacity of up to 800℃,which has important application prospects in large and complex structural components such as engine casings.As the main grain boundary strengthening phase in this alloy,the evolution of carbides during the long-term aging process is still unclear.This article takes K439B alloy as the object and conducts isothermal aging experiments at 800℃ for 6000—10000 h to study the evolution and transformation mechanism of carbides during long-term aging process.The results indicate that K439B alloy has excellent structural stability.After long-term aging,most of the MC type carbides in the standard heat treated state were still retained in the grain boundaries and interdendritic structures,and only a portion of the MC type carbides decomposed into M_(23)C_(6)-type carbides and·phase,no harmful phases(e.g.σandη)were formed after long-term aging for 10000 h.The M_(23)C_(6)-type carbides at grain boundaries exhibited two coarsening behaviors.On the one hand,the M_(23)C_(6)-type carbides gradually coarsened and had a uniform width after long-term aging;on the other hand,the coarsened M_(23)C_(6)-type carbides at certain grain boundaries exhibited irregular shapes and even extended towards the interior of the grains.γ′phase separate two adjacent M_(23)C_(6)-type carbides,resulting in no complete connection of M_(23)C_(6)-type carbides along the entire grain boundaries.

关 键 词：K439B镍基高温合金 长期时效 组织稳定性 碳化物 

分 类 号：TG132.3[一般工业技术—材料科学与工程]