Atomic simulations of melting behaviours for TiAl alloy nanoparticles during heating
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Bull Mater Sci (2020)43:241 https://doi.org/10.1007/s12034-020-02193-5
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Atomic simulations of melting behaviours for TiAl alloy nanoparticles during heating YIN XIANGYANG1,2, YAO QI2, LIU JUNJUN1,2 and ZHANG LIN1,2,3,* 1
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China 2 The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China 3 Department of Materials Physics and Chemistry, School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China *Author for correspondence ([email protected]) MS received 15 March 2020; accepted 26 May 2020 Abstract. Titanium alloys not only have a high strength to weight ratio and good corrosion resistance but also have a higher cost on traditionally metallurgy. In additive manufacturing (AM) process, the thermal stability of alloy particles during heating has an important influence on fabricating parts. This article presents atomic simulations to study changes of packing structures and atomic level stresses by using a molecular dynamics (MD) approach within the framework of embedded atom method (EAM). This research provides different evolution patterns of TiAl nanoparticles with different sizes owing to the following facts that the atoms undergo different strain states. In these particles, a large proportion of Al atoms are subjected to tensile or compressive strain, whereas a considerable number of Ti atoms are stretched or compressed only at high temperatures. Back propagation neural network is used to calculate data of specific heat, and the machine learning provides the possibility to determine critical size suitable for the classical Dulong–Petit law under certain thermal conditions. Keywords.
1.
Atomic modelling; molecular dynamics; TiAl; nanoparticles.
Introduction
c-TiAl intermetallic compound has important applications in aerospace and automobile parts owing to its many advantages, including high specific Young’s modulus, strength, low density, high melting temperature, excellent oxidation and corrosion resistances [1,2]. In structure–processing–property–performance relationships for this alloy, the goal is to achieve the service performances at higher temperatures in developing or designing advanced c-alloy technology by combining process with microstructure to improve the reliability and manufacturability in these applications. However, the production of the target-oriented alloy is hampered by traditionally casting and forging metallurgy. Additive manufacturing (AM) integrates materials science, mechanism engineering and computer technology, which has made it possible to accurately fabricate titanium alloy products with complex morphologies, relatively low number and shorter manufacturing time [3–14]. Under the control of one computer, pre-alloy particles on the powder-bed undergo rapidly heating from power thermal sources, and then this layer-by-layer manufacturin
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