摘要
通过对等温锻造GH4169G合金进行直接时效处理、蠕变性能测试和组织形貌观察,研究了GH4169G合金的组织结构及蠕变行为。结果表明:经等温锻造和直接时效后,GH4169G合金晶粒具有不均匀特征,且在晶内存在孪晶,并有粒状δ相在晶内及沿晶界不连续析出,可改善晶界的结合强度。经不同条件蠕变性能测试后,根据稳态蠕变期间的应变速率,测定出合金在稳态期间的蠕变激活能和应力指数分别为Q=532.7 kJ/mol和n=12.1。合金在蠕变期间的变形特征是不同取向的孪晶变形和位错滑移,随蠕变进行,形变位错密度增加,且在晶界附近发生位错堆积,并产生应力集中,致使微裂纹在晶界处萌生及扩展,直至蠕变后期发生沿晶断裂。
Microstructure and creep behavior of the ITF-DA-GH4169G alloy were investigated by means of the creep properties measurement and microstructure observation. Results show that after isothermal forging （ITF） and direct aging （DA） treatment, the grains of GH4169G alloy present an un-homogeneous feature, twinning occurs within the grains. And the particle-like phase is discontinuously precipitated along grain boundaries and within the grains, which strengthens the grain boundaries to enhance creep resistance of the alloy. The activation energy and stress exponent of the alloy during steady state creep are determined to be Q = 532. 7 kJ/mol and n = 12. 1, respectively, based on the creep experiment. The creep deformation of the alloy is characterized by twinning in different orientations and slipping of dislocations activated in the matrix. As continuance of creep deformation grain, the density of dislocations increases, and some dislocations are piled up in the regions near boundaries to cause stress concentration, which promotes the initiation and propagation of micro-cracks along the boundaries, up to the occurrence of creep fracture along grain boundaries in the later stage of creep.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第8期74-79,共6页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金资助的重点项目(50634030)
