Nb、Al含量对GH706合金组织及力学性能的影响

Effects of Al and Nb Content on Microstructure and Properties of GH706 Alloy

摘要:

研究了降Nb提Al对GH706合金组织和力学性能的影响。当合金中Al含量由0.35%提高至1.26% (质量分数, 下同)，Nb含量由2.88%降低至1.98%后，可抑制晶内主要强化相γ″-Ni3Nb相的析出，促进γ′-Ni3Al相的析出，显著降低合金的室温屈服强度，但明显改善了合金的室温冲击性能。同时提Al降Nb还抑制了晶界强化相η-Ni3(Ti, Nb)相的析出，使得富Nb的Laves相及富Nb、Cr的Cr2Nb相析出，弱化了高温下的晶界强度，极大地恶化了合金的持久性能

Abstract:

The effects of increasing Al and decreasing Nb on microstructure and mechanical properties of GH706 alloy were studied. With increasing Al from 0.35% to 1.26% and decreasing Nb from 2.88% to 1.98%, the precipitation of γ″-Ni3Nb phase is constrained, while the formation of γ′-Ni3Al phase is promoted. As a result, the tensile strength at room temperature is decreased, but the impact energy is improved. However, such a modification of Al and Nb constrains the precipitation of intergranular η-Ni3(Ti,Nb) phase, and enhances the precipitation of Laves phase rich in Nb and Cr2Nb phase rich in Nb and Cr, which decreases the grain boundary cohesion and deteriorates the stress rupture properties at 650 oC and 690 MPa