FGH95镍基合金的蠕变行为及影响因素

Creep Behavior and Influencing Factors of FGH95 Nickel Base Superalloy

摘要:

通过蠕变曲线测定和组织形貌观察，研究FGH95合金的蠕变行为及影响因素。结果表明：经1150 ℃固溶和时效处理后，在晶界处有粗大γ′相不连续分布，其周围存在γ′相贫化区；经1165 ℃固溶和时效后，合金的晶粒尺寸明显长大，并在晶界形成连续的碳化物膜；经1160 ℃固溶后，合金中无粗大γ′相，在晶内弥散析出细小γ′相，其中，有粒状(Nb, Ti) C相在晶内及沿晶界不连续析出，可提高合金的晶界强度，抑制晶界滑移，是使合金具有较好蠕变抗力的主要原因。蠕变期间，合金的变形机制是位错剪切或绕过γ′相，蠕变后期，在晶内发生单取向和双取向滑移，并引起应力集中，致使裂纹在晶界处萌生及扩展是合金的蠕变断裂机制

Abstract:

By means of the measurement of creep curves and microstructure observation, the creep behavior and influencing factors of FGH95 nickel-base superalloy has been investigated. Results show that after the solution treatment at 1150 oC and aging, some coarse g ￠ precipitates are discontinuously distributed in the grain boundary region and around them is the depleted zone of the finer g ￠ phase. However, after the solution treatment at 1165 oC and aging, the grains are obviously grown up, and the films of the carbide are continuously precipitated along the boundaries. After the solution treatment at 1160 oC and aging, the coarse g ￠ phase in the alloy is fully dissolved, the finer g ￠ phase is dispersedly distributed within the grains, and some particles of (Nb,Ti)C phase are discontinuously precipitated in the grains and along the boundaries, which is thought to be the main reason for better creep resistance due to the pinning effect of them to restrain the boundaries slipping. The deformation mechanism of the alloy during creep is the dislocation shearing or bypassing the g ￠ phase. In the later creep stage, the deformation features of the alloy are the single-orientation and double-orientations slipping of dislocations activated in the alloy, which brings out the stress concentration to promote the initiation and propagation of the micro-cracks along the boundaries, and it is thought to be the fracture mechanism of the alloy during creep