Sintered Ti/Al core/shell nanoparticles: computational investigation of the effects of core volume fraction, heating rate, and room-temperature relaxation on tensile properties

HD Zhang and J Jeon and F Rahmani and S Nouranian and S Jiang, JOURNAL OF PHYSICS D-APPLIED PHYSICS, 55, 025302 (2022).

DOI: 10.1088/1361-6463/ac2ad7

Molecular dynamics simulations were performed to roughly imitate the conditions of selective laser sintering during additive manufacturing. The role of core volume fraction on the resultant uniaxial tensile properties of sintered Ti/Al bimetallic core/shell nanoparticles (NPs) was investigated during various sintering states. A chain model was created from five single thermally equilibrated Ti/Al NPs with weak neck connections by a solid-state sintering process at room temperature (298 K). The chains were heated to 800 K with two heating rates (0.04 and 0.2 K ps(-1)), underwent high-temperature relaxation, and were cooled to 298 K with a cooling rate of 0.08 K ps(-1). They were then relaxed at 298 K for different periods (i.e. 1, 4, and 10 ns). In a follow-up procedure, those sintered NPs were subjected to uniaxial tension at different strain rates (i.e. 0.001, 0.01, and 0.1% ps(-1)). The thermodynamic properties and the structural evolutions of atomic configurations were investigated during the sintering process. The tensile responses were also obtained to examine the final product quality. The results indicate a strong correlation between the tensile strength of the final sintered chain product and the Ti core volume fraction. A larger Ti core volume fraction yields a stronger chain structure, resulting in higher tensile strength. The effect of heating rate on the tensile strength of final products with larger core volume fraction is more pronounced. The effect of room-temperature relaxation is not obvious on the tensile strength except for two products, which were sintered with the fast heating rate and tested under the lowest/highest strain rate. Also, high strain rates improve the tensile strength, and low strain rates will lead to enhanced ductility of the final products, especially with residual single atomic chain.

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