Laser metal deposition of Al0.6CoCrFeNi with Ti & C additions using elemental powder blends

SURFACE & COATINGS TECHNOLOGY

卷:418

Article

Asabre, Alex¹  Wilms, Markus B.²  Kostka, Aleksander³  Gemagami, Parham¹  Weisheit, Andreas²  Laplanche, Guillaume¹ 

[1] Ruhr Univ Bochum, Inst Werkstoffe, D-44780 Bochum, Germany

[2] Fraunhofer Inst Laser Technol ILT, D-52074 Aachen, Germany

[3] Ruhr Univ Bochum, Zentrum Grenzflachendominierte Hochstleistungswer, Bochum, Germany

关键词: High-entropy alloys;    Compositionally complex alloys;    Additive manufacturing;    Laser cladding;    Mechanical properties;    Tool steel substrate;   

DOI  :  10.1016/j.surfcoat.2021.127233

来源: Elsevier

【 摘 要 】

Laser metal deposition (LMD) was used to in-situ alloy a crack-free Al-0.6 CoCrFeNi compositionally complex alloy (CCA) with 3 at.% Ti and 0.25 at.% C additions on an initially ferritic H10 tool steel from an elemental powder blend. After LMD, the material was annealed at 900 degrees C for 30 min to induce martensitic hardening in the substrate. The CCA in both as-deposited and annealed states exhibited a lamellar microstructure consisting of four phases: a matrix of interwoven disordered and ordered body-centered cubic phases, titanium carbides distributed randomly within the microstructure, and disordered face-centered cubic (FCC) plates that precipitated at the grain boundaries and grew towards the center of the grains. Chemical analyses along the build-up direction of the coating revealed a compositional gradient, similar in both as-deposited and annealed states, due to the intermixing between the substrate and the CCA. Despite a strong variation of the Fe-content, the hardness and the microstructure remain roughly constant in the major part of the as-deposited coating, which contains a large fraction of FCC plates that are beneficial to increase ductility and ensure a good compatibility with the substrate. In contrast, the upper part of the as-deposited coating, corresponding to the last solidified melt pool after LMD, has a much lower FCC fraction with an enhanced hardness. After annealing, the hardness of the tool steel substrate significantly increased and the FCC volume fraction in the coating increased from similar to 16% (as-deposited) to similar to 58%. Overall the microstructure of the coating became more homogeneous while its hardness decreased only by 10-15%. These results demonstrate that the CCA can be employed as a protective coating on a less expensive tool steel to improve its lifetime during service.

【 授权许可】

Free