A functionally graded material design from stainless steel to Ni-based superalloy by laser metal deposition coupled with thermodynamic prediction. (May 2022)

• Record Type: Journal Article
• Authors: Li, Kun; Zhan, Jianbin; Zhang, Ming; Ma, Ruijin; Tang, Qian; Zhang, David Z.; Murr, Lawrence E.; Cao, Huajun
• Is Part Of: Materials & design. Volume 217(2022)
• Publication Date: 2022-05
• Subjects: Functionally graded materials -- Laser directed energy deposition -- Microstructure-property relationship -- Precipitation behavior -- High throughput design; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2022.110612
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: The functionally graded material from SS316 to IN718 without cracks and distortions is built using the laser direct energy deposition. The aging precipitation behaviors in the SS316/IN718 functionally graded material are systematically studied for the first time. The high throughput thermodynamic is performed to analyze the experimental results in the functionally graded material. The control of precipitation is proposed to tune the mechanical properties of the additively manufactured functionally graded materials. Abstract: Extreme performance requirements are demanding materials with functional microstructure and properties. Additive manufacturing (AM) is an efficient method to fabricate functionally graded materials (FGMs) with gradually variable composition and structures as a function of position. In this work, a powder-based laser directed energy deposition (LDED) process was carried out to develop a series of compositionally graded joints from 316 stainless steel to Inconel 718 alloy. The microstructure, composition, precipitation transformation and mechanical properties were investigated as a function of position in FGMs via experimental characterization and computational analysis. The 75 wt% IN718 component with fine and equiaxial grains is directly obtained from the laser deposition. The diffusion and segregation of Ni, Nb and Ti elements underly the transformation mechanism between Laves, NbNi3 /δ, γ'' and γ'' phases during aging, which has a high consistency with the computational prediction. The precipitation transformation has a close relationship with the final mechanical properties of the FGM. The computational-experimental approach is a promising method to tune the microstructure-property relationship of dissimilar metal joints. The gradient precipitation that can be flexibly tuned by LDED process provides a high throughput design to develop new functional materials with local tailoring of properties.