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LASER GLAZING RAPIDLY SOLIDIFIED MICROSTRUCTURE OF DD8 SINGLE CRYSTAL Ni-BASED SUPERALLOY
Jin Tao; Sun Xiaofeng; Zhao Nairen; Liu Jinlai; Zhang Jinghua; Hu Zhuangqi
Corresponding AuthorJin Tao(tjin@imr.ac.cn)
2009-06-01
Source PublicationACTA METALLURGICA SINICA
ISSN0412-1961
Volume45Issue:6Pages:711-716
AbstractThe laser glazing rapid solidification call make the dendrite refined and reduce the segregation of alloying elements, so it is very favorable to mechanical properties of allo e.g, the fatigue life of Ni-based superalloy call be prolonged by laser surface melting process due to improved resistance to stress corrosion cleavage. The, laser surface melting process call be used for modification of surface or repair of casting defects (such as surface porosity, surface stray grains) ill single crystal components. Recently this technique has become an attractive research subject with latent application. A successful laser glazing rapid solidification to single-crystal should ensure Hie preservation of the single-crystal nature i.e., the re-solidified surface layer needs to be epitactic with the substrate. The microstructure after laser re-solidification is closely related to the processing, parameters, however, the relationship between microstructure and re-solidification conditions or processing parameters is not well understood and needs further study. Ill the present work, the microstructure of laser glazing solidified Ni-based single crystal DD8 was investigate(I 1)by OM, SEM as well as TEM. The results show that the surface width of the melted pool becomes narrow with an increase of scanning rate, so the melted pool has a relatively high interface/volume ratio which leads to a higher cooling rate. The primary dendrite arm spacing decreases with an increase, of cooling rate, and gradually reaches a minimum about only 3 mu m, which is two orders of magnitude smaller than that of the untreated part, of alloy. EDXA shows that the dendritic segregation is not obvious and the chemical compositions tend to be homogeneous after re-solidification, which is caused by the higher solidification rate, and related partition coefficients of alloying elements. The solidified structures are composed of the quasi-plane front, cellular and fine dendrites from substrate to surface of melted pool. The structures in the regions of the quasi-plane front and cellular consist of gamma-solid solution and dispersive gamma' precipitates with about 20 nm in size. In the re-ions of the cellular-dendrite and the dendrite, however, there is a eutectic structure with a higher Ti content in the, interdendrites. These eutectic structures are small in size and look like leaves. In the transition region, both gamma and gamma'-phases are not, completely melted and there axe some dislocations distributed oil the interface of the gamma'-phase particles induced by thermal stress between gamma and gamma' phases at higher cooling rate. The unmelted gamma' particles can act as nuclei of the second precipitated gamma' phases which have a size of about 10 nm and a pile-up-like morphology.
KeywordNi-based superalloy single crystal laser glazing rapid solidification microstructure
Indexed BySCI
Language英语
WOS Research AreaMetallurgy & Metallurgical Engineering
WOS SubjectMetallurgy & Metallurgical Engineering
WOS IDWOS:000268359700012
PublisherSCIENCE PRESS
Citation statistics
Cited Times:2[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.imr.ac.cn/handle/321006/98211
Collection中国科学院金属研究所
Corresponding AuthorJin Tao
AffiliationChinese Acad Sci, Inst Met Res, Shenyang 110016, Peoples R China
Recommended Citation
GB/T 7714
Jin Tao,Sun Xiaofeng,Zhao Nairen,et al. LASER GLAZING RAPIDLY SOLIDIFIED MICROSTRUCTURE OF DD8 SINGLE CRYSTAL Ni-BASED SUPERALLOY[J]. ACTA METALLURGICA SINICA,2009,45(6):711-716.
APA Jin Tao,Sun Xiaofeng,Zhao Nairen,Liu Jinlai,Zhang Jinghua,&Hu Zhuangqi.(2009).LASER GLAZING RAPIDLY SOLIDIFIED MICROSTRUCTURE OF DD8 SINGLE CRYSTAL Ni-BASED SUPERALLOY.ACTA METALLURGICA SINICA,45(6),711-716.
MLA Jin Tao,et al."LASER GLAZING RAPIDLY SOLIDIFIED MICROSTRUCTURE OF DD8 SINGLE CRYSTAL Ni-BASED SUPERALLOY".ACTA METALLURGICA SINICA 45.6(2009):711-716.
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