Liquation cracking facilitated by stray-grain chains in a high-γ'-content nickel-based alloy K4002 produced via electron beam powder bed fusion

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization Pub Date : 2024-12-01 DOI:10.1016/j.matchar.2024.114589

Yunting Li , Maodong Kang , Yang Zhou , Yuantao Xu , Huipeng Yu , Yufei Pan , Jun Wang , Chengqi Zhang

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Abstract

Cracking significantly hinders the development of additive manufactured high-γ’-content nickel-based alloys. This study investigates the microstructure and cracking behavior of a high-γ'-content nickel-based alloy K4002 produced via electron beam powder bed fusion (EBPBF). The results suggest that liquation cracking is the predominant cracking mechanism observed. Stray-grain chains were found to promote liquation cracking due to several factors: i) The presence of high angle grain boundaries (HAGBs) between the stray grains and adjacent columnar grains; ii) the higher density of geometrically necessary dislocations (GND) within stray grains; iii) Cr₂₃C₆ carbides, at the stray grain boundaries, hinder dislocation motion and promote strain accumulation; and iv) the formation of low-melting-point regions around the Cr₂₃C₆ within the stray grain chains. Furthermore, the origin of stray-grain chains was analyzed using the Rayleigh number and the columnar-to-equiaxed transition (CET) criterion, revealing that the stray-grain chains originate from the CET. As a result, through optimizing the solidification rate to inhibit CET, stray-grain chains were effectively eliminated, leading to a 55 % reduction in crack incidence. The findings in this work provide guidance for mitigating liquation cracking induced by stray-grain chains during additive manufacturing.

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电子束粉末床熔合制备的高γ′含量镍基合金K4002中杂散晶链的溶解开裂

裂纹严重阻碍了增材制造高γ′含量镍基合金的发展。研究了采用电子束粉末床熔合法制备的高γ′含量镍基合金K4002的显微组织和开裂行为。结果表明，液化开裂是主要的开裂机制。发现散失晶粒链促进液化开裂的原因有以下几个：1)散失晶粒与相邻柱状晶粒之间存在高角晶界（HAGBs）；ii)杂散颗粒中几何必要位错（GND）的密度更高；iii) Cr23C6碳化物在杂散晶界处阻碍位错运动，促进应变积累；杂散晶粒链中Cr23C6周围形成低熔点区域。此外，利用瑞利数和柱向等轴转变（CET）准则分析了散粒链的起源，揭示了散粒链起源于CET。结果表明，通过优化凝固速率抑制固相损伤，有效地消除了散晶链，使裂纹发生率降低了55%。本工作的发现为减轻增材制造过程中由散粒链引起的液化开裂提供了指导。

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来源期刊

Materials Characterization 工程技术-材料科学：表征与测试

CiteScore

7.60

自引率

8.50%

发文量

746

审稿时长

36 days

期刊介绍： Materials Characterization features original articles and state-of-the-art reviews on theoretical and practical aspects of the structure and behaviour of materials. The Journal focuses on all characterization techniques, including all forms of microscopy (light, electron, acoustic, etc.,) and analysis (especially microanalysis and surface analytical techniques). Developments in both this wide range of techniques and their application to the quantification of the microstructure of materials are essential facets of the Journal. The Journal provides the Materials Scientist/Engineer with up-to-date information on many types of materials with an underlying theme of explaining the behavior of materials using novel approaches. Materials covered by the journal include: Metals & Alloys Ceramics Nanomaterials Biomedical materials Optical materials Composites Natural Materials.