导　　师： 田素贵;尚丽娟

学科专业： 080502

授予学位： 硕士

作　　者： ;

机构地区： 沈阳工业大学

摘　　要： 通过对FGH95粉末镍基合金进行不同条件的热处理、蠕变性能测试及组织形貌观察,研究了热处理制度对合金组织结构与蠕变性能的影响,及合金在蠕变期间的变形与断裂机制。 结果表明:在1050℃及1140℃进行粉末预处理和1150℃热等静压处理,获得的一次γ'相尺寸较小,并沿晶界均匀分布。合金分别采用“标准”、“空冷”和“油冷”热处理后,一次粗大γ'相存留在较宽的晶界区域,二次γ'相在晶内析出;与“标准”热处理相比,“空冷”热处理合金中晶内的二次γ'相尺寸较小,且均匀分布;其中,一次粗大γ'相沿晶界析出,且沿晶界存在γ'相贫化区是降低合金蠕变抗力的主要原因。与“油冷”处理合金相比,“盐浴”处理合金的组织结构是细小γ'相弥散分布在晶内,其中沿晶界不连续析出的细小/(Nb,Cr/)C和/(Cr,W/)/_/(23/)C/_6型碳化物可提高晶界的结合强度,有效阻碍位错运动,提高合金的蠕变抗力。与“油冷”处理合金相比较,“盐浴”处理合金具有较好的蠕变强度和较长的蠕变寿命;在实验的温度和应力范围内,测定出“油冷”和“盐浴”处理合金的蠕变激活能分别为:Q=381.1kJ//mol和Q=542.07kJ//mol。在蠕变断裂期间,“油冷”热处理合金的变形特征是位错在晶内发生单取向或双取向滑移,在滑移迹线区域有细小碳化物析出,并发生γ'相贫化区的碎化,而在“盐浴”处理合金中仅发生晶内的位错滑移。在蠕变期间,合金的微观变形特征是孪晶和位错在晶内发生双取向滑移,并确定出孪晶面为/(111/)晶面,其中切入γ'相内的<110>超位错可分解形成/(1//3/)<112>超肖克莱不全位错+层错的位错组态。“盐浴”处理合金蠕变期间的断裂特征是发生穿晶和沿晶混合断裂,其中沿晶断裂呈现的非光滑晶粒表面是由于沿晶界析出的细小碳化物所致。 In the papcr,by means of heat trcatmcnt,creep properties measurement and microstructurc observation,an invcstigation has been made into the influcncc of heat treatment regimes on the microstructurc,creep properties,deformation and fracture mechanisms of FGH95 powder nickel-base supcralloy during creep. Results show that after the powder prc-treatcd at 1050℃and 1140℃,and hot isostatic prcssurc at 1150℃,thc alloy obtains the microstructurc in which the thickcrγ′phase is distributed in the boundaries region and the finerγ′phase precipitated with the grain.After using 'standard','air cooling' and 'oil cooling' heat treatment,the thickerγ′phase is kept in the wider boundary regions,the finerγ' phase is dispersely precipitated with the grains. Compared to 'air cooling' heat treatment,after 'standard' heat treatment,the thickerγ′phase is precipitated along the boundaries to form the poor region ofγ′phase,which is a main reason of decreasing creep resistance of the alloy.Compared to 'oil cooling' heat treatment,after 'salt-cooling' heat treatment,the alloy obtains the microstructure in which the finerγ′phase is dispersely distributed within the grain,thereinto,the fact that the finer /(Nb,Cr/)C and/(Cr,W/)/_/(23/)C/_6 carbide particles are discontinuously precipitated on the grain boundaries to improve the combined strength,which may hinder the dislocation movement and enhance the creep resistance of the alloy,therefore,the 'salt cooling' treated alloy displays a longer creep lifetimes.In the range of the applied temperatures and stresses,the activation energies and stress exponents of the 'oil cooling' and 'salt cooling' heat treated alloys during creep are calculated to be Q/_a = 381.1kJ//mol and Q/_a = 542.07kJ//mol, respectively.During creep,the deformed features of the 'oil cooling' treated alloy is the single and double orientations slipping of dislocations activated within the grains,and the fragmentation of the wider boundaries occurs in the region ofγ′phase.But only dislocation slipping is detected in the grain of the 'salt cooling' treated alloy.During creep, the deformed features of the alloy is twinning and dislocation slipping activated within the twins,thereinto,the <110> super-dislocation shearing into theγ′phase may be decomposed to form the configuration of/(1//3/)<112> super-shockleys dislocation,and the stacking fault.And the fracture features of the alloy is the occurrence of the intergranular and cross-granular fracture,thereinto,the nonsmooth surface appeared in the fracture region is attributed to the finer carbides precipitated along the boundary.

关 键 词： 粉末镍基合金 制备工艺 组织结构 蠕变 变形机制

分 类 号： [TG131]

领　　域： [金属学及工艺] [一般工业技术] [金属学及工艺]