Phase constitution, microstructure and mechanical properties of a Ni-based superalloy specially designed for additive manufacturing

• Published in: China foundry Vol. 18; no. 4; pp. 397 - 408
• Main Authors: Wu, Bin, Liang, Jing-jing, Yang, Yan-hong, Li, Jin-guo, Zhou, Yi-zhou
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.07.2021; Space Manufacturing Technology(CAS Key Lab),Beijing 100094,China%Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China; School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China%Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China; Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China
• Subjects: Engineering; Machines; Manufacturing; Materials Engineering; Metallic Materials; Processes; Research & Development; laser metal deposition; A; additive manufacturing; 5; tensile behavior; Ni-based superalloy; TG146.1
• ISSN: 1672-6421; 2365-9459
• DOI: 10.1007/s41230-021-9025-1

In this study, a kind of Ni-based superalloy specially designed for additive manufacturing (AM) was investigated. Thermo-Calc simulation and differential scanning calorimetry (DSC) analysis were used to determine phases and their transformation temperature. Experimental specimens were prepared by laser metal deposition (LMD) and traditional casting method. Microstructure, phase constitution and mechanical properties of the alloy were characterized by scanning electron microscopy (SEM), transmission scanning electron microscopy (TEM), X-ray diffraction (XRD) and tensile tests. The results show that this alloy contains two basic phases, γ/γ’, in addition to these phases, at least two secondary phases may be present, such as MC carbides and Laves phases. Furthermore, the as-deposited alloy has finer dendrite, its mean primary dendrite arm space (PDAS) is about 30–45 μm, and the average size of γ’ particles is 100–150 nm. However, the dendrite size of the as-cast alloy is much larger and its PDAS is 300–500 μm with secondary and even third dendrite arms. Correspondingly, the alloy displays different tensile behavior with different processing methods, and the as-deposited specimen shows better ultimate tensile stress (1,085.7±51.7 MPa), yield stress (697±19.5 MPa) and elongation (25.8%±2.2%) than that of the as-cast specimen. The differences in mechanical properties of the alloy are due to the different morphology and size of dendrites, γ’, and Laves phase, and the segregation of elements, etc. Such important information would be helpful for alloy application as well as new alloy development.