力學性能的影響
(中國科學院 金屬研究所，沈陽 110016)
摘 要: 研究Hf對抗熱腐蝕鎳基高溫合金組織和力學性能的影響；探討組織演化和力學性能的關系，對于Hf的添加對γ′筏形化和γ/γ′錯配度的影響也進行討論。結(jié)果表明：與無Hf合金相比，含0.4%Hf(質(zhì)量分數(shù))合金的組織晶界上存在較少的大塊狀MC碳化物，而細小M23C6碳化物的含量更多，這對蠕變性能有利；Hf的添加有助于使MC碳化物的數(shù)量在蠕變過程中保持較高的水平；在長期時效過程中，晶界上碳化物分解為細小離散分布的M23C6碳化物，沿著晶界形成γ′層，無Hf合金的晶界粗化現(xiàn)象更為明顯；Hf的添加可以提升合金長期時效后的高溫拉伸性能；同時，Hf對提高低應力條件下的蠕變強度作用明顯。
關鍵字: 鑄造鎳基合金；高溫合金；晶界組織；力學性能；錯配度；筏形化
hot corrosion resistant Ni-based superalloys
（Institute of Metals Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The effect of the selective addition of Hf on the mechanical properties and microstructures of experimented nickel superalloy was investigated. The relationship between the microstructure evolution and mechanical properties was studied. Furthermore, the relationship of the appearance of rafting and lattice misfit with regards to Hf content was discussed. The results show that mainly small, coherent, blocky and closely spaced MC and M23C6 carbides precipitate on the grain boundaries in the 0.4% (mass fraction) Hf-contained alloy, and that relatively larger, incoherent MC carbides precipitate on the grain boundaries in the Hf free alloy. During the long-term thermal exposure, fine discrete M23C6 carbides decompose from primary carbide, inducing γ′ layer along the grain boundary, and the coarsening of grain boundary in Hf free alloy is more evident. The selective addition of Hf is beneficial to high temperature tensile strength, and the benefit of Hf content is significant at low stresses.
Key words: cast Ni-based alloy; superalloy; grain boundary microstructure; mechanical property; lattice misfit; rafting
