激光冲击强化对镍基单晶高温合金微观组织和抗高温氧化性能的影响

Influence of Laser Shock Peening on Microstructure and Oxidation Performance of Nickel-based Single Crystal Superalloy

研究了激光冲击强化(LSP)对镍基单晶高温合金微观结构和氧化性的影响,首先对试样进行LSP处理,随后将试样置于980℃下进行10和150 h的氧化实验,对比分析了原始和LSP试样的微观结构、显微硬度和氧化形貌演变,最后探讨了LSP对该合金氧化性能的影响。结果表明,1次冲击后,样品表面引入了网状分布的位错,表面显微硬度从原始的420 HV增加到495 HV;3次冲击后,表面位错分布更加均匀密集,出现了位错缠结,表面显微硬度增加到约590 HV。此外,LSP在表面产生的位错为氧化过程提供了扩散通道,促进了连续的保护性氧化膜的形成,从而减少了贫Al孔洞的形成并增加了氧化膜抗剥落能力。

The impact of laser shock peening(LSP)on the microstructure and oxidation behavior of the nickel-based single crystal superalloy was investigated.The samples underwent LSP treatment,followed by oxidation for 10 and 150 h at 980oC.The microstructure,microhardness,and oxidation morphology of this alloy without and with LSP treatment were comparatively examined.Finally,the mechanism by which LSP affects the oxidation behavior of this alloy was elucidated.The result shows that after a single impact,the surface of the specimen manifested some grid-like dislocations distribution,alongside an increment in microhardness from an initial value of 420 HV to 495 HV.After three impacts,the dislocations on the surface appeared more uniformly distributed with evident entanglement,culminating in an elevation of surface microhardness to approximately 590 HV.Furthermore,the dislocations generated on the surface by LSP promoted the formation of diffusion pathways during the oxidation process,which facilitated the early formation of a continuous protective oxide scale.It decreased the formation of poor Al pits,which resulted from the development of a protective oxide scale in the subsequent stages of oxidation,thereby reducing the spalling of the oxide scale.