Strengthening and toughening effect of laser melting deposited Nb–16Si–20Ti–3Al with nano-ZrC additions

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 850; p. 143509
• Main Authors: Yin, Xiuyuan, Liang, Jing, Jia, Xinyu, Chen, Suiyuan, Shang, Shuo, Sui, Yi, Liu, Changsheng
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 11.08.2022; Elsevier BV
• Subjects: Alloys; Compressive properties; Compressive strength; Eutectics; Fracture toughness; Grain boundaries; Laser beam melting; Laser Melting Deposited (LMD); Microstructure; Nano-ZrC; Nb–Si based alloy; Niobium base alloys; Phase composition; Solid solutions; Zirconium carbide; Laser Melting Deposited (LMD); Microstructure; Nano-ZrC; Nb–Si based alloy; Fracture toughness
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2022.143509

The phase composition, microstructure, and properties of Laser Melting Deposited (LMD) Nb–16Si–20Ti–3Al alloys with different nano-ZrC (0, 2.5, 5.0, 10.0 wt%) addition were detailed investigated in this study. Results showed that the LMDed Nb–16Si–20Ti–3Al alloy was composed Nb-based solid solution (Nbss) and Nb3Si. The addition of nano-ZrC promoted the decomposition of the Nb3Si phase and the eutectic transformation from Nb3Si to (Nbss+γ-Nb5Si3) eutectic structure. With the content of nano-ZrC increased from 2.5 wt% to 5.0 wt%, the (Nbss+γ-Nb5Si3) eutectic structure was significantly refined. Nb-rich TiC phase precipitated at the grain boundaries of (Nbss+γ-Nb5Si3) eutectic structure by the titanium in the alloy reacted with nano-ZrC additions. With the content of nano-ZrC increased to 10.0 wt%, coarse and irregular primary γ-Nb5Si3 phase and dendritic TiC were observed in the Nb–Si alloy. The fracture toughness was improved from 5.1 MPa m½ to 17.1 MPa m½ by adding an optimized amount of nano-ZrC (5.0 wt%) due to the refinement of (Nbss+γ-Nb5Si3) eutectic structure and dispersion distributed nano-ZrC in the alloys. The Nb–16Si–20Ti–3Al alloy with 5.0 wt% nano-ZrC addition has the maximum compressive strength of 1836 MPa and a compressive strain of 12.6%. The crack deflection seems an important toughening mechanism for Nb–16Si–20Ti–3Al alloys containing nano-ZrC. The fracture mode of each Nb–16Si–20Ti–3Al alloys with (0, 2.5, 5.0, 10.0 wt%) addition exhibited a brittle quasi cleavage fracture. •Nano-ZrC is first introduced to improve the Nb–Si alloys.•Nano-ZrC as a heterogeneous nucleating agent promoted the silicide phase formation.•The addition of nano-ZrC refined the Nbss + Nb5Si3 eutectic structure.•The micro-nano structure significantly improves the properties of the Nb–Si alloys.