2021 №06 (03) DOI of Article
2021 №06 (05)

Automatic Welding 2021 #06
Avtomaticheskaya Svarka (Automatic Welding), #6, 2021, pp. 29-34

Structure of laser welded joints of multicomponent high-entropy alloy of Nb-Cr-Ti-Al-Zr system

V.D. Shelyagin1, A.V. Bernatskyi1, O.V. Siora1, V.I. Bondarieva1, M.P. Brodnikovsky2

1E.O. Paton Electric Welding Institute. 11 Kazymyr Malevych Str., 03150 Kyiv, Ukraine. E-mail: office@paton.kiev.ua
2I.M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine. 3 Krzhyzhanovskyi Str., 0312, Kyiv.

In the work the authors studied the problems of laser welding of joints of high-entropy alloy of Nb–Cr–Ti–Al–Zr system. The results of differential thermal analysis of the initial material are presented. Results of X-ray phase analysis of the alloy were analyzed. A conclusion was made about existence of bcc solid solution based on niobium and solid solution based on ZrCr 2 intermetallics in the alloy, as well as existence of two niobium-based solid solutions with different chemical composition in the alloy. Analysis of the influence of alloy crystallization rate on its microstructure was performed. It is shown that the ratio of the quantity of dendrites and eutectic can change, depending on the cooling rate. Obtained investigation results on formation of a dendrite structure were furtheron used at optimization of laser welding modes. In this work the authors studied the influence of such parameters as radiation power and laser welding speed on weld microstructure formation. Mechanical properties of butt joints at uniaxial static tension were studied. It was found that material softening which leads to destruction, is influenced by the feature of distribution of residual thermal stresses that is determined by the mode of heat input and removal during welding. It is shown that formation of the majority of the defects is related to a feature of nonequilibrium crystallization of multicomponent high-entropy high-temperature alloys. In order to prevent their formation, it is rational to take measures for optimizing the technology parameters, aimed at increasing the melt cooling rate, in order to produce a more equilibrium structure. 15 Ref., Fig. 5.
Keywords: multicomponent high-entropy alloy, laser welding, butt joints, structure, mechanical properties, defects

Received: 21.04.2021


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