Title£º Phase-field simulation of competitive growth of grains in a binary alloy during directional of grains in a binary alloy during directional
Author£º *Li Feng1, 2, Ya-long Gao1, Ni-ni Lu1, Chang-sheng Zhu2, Guo-sheng An1, 2, Jun-he Zhong1
Address£º 1. College of Materials and Engineering, Lanzhou University of Technology, Lanzhou 730050, China 2. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
Key words£º phase-fi eld method; binary alloy; directional solidifi cation; different planes; competitive growth
CLC Nmuber£º TP391.9
Document Code£º A
Article ID£º 1672-6421(2018)05-333-10
Abstract£º

Taking Al-2%mole-Cu binary alloy as an example, the infl uence of grain orientation on competitive growth of dendrites under different competitive modes was investigated by using the three-dimensional (3-D) phasefield method. The result of phase-fi eld simulation was verifi ed by applying cold spray and directional remelting. In the simulation process, two competitive modes were designed: in Scheme 1, the monolayer columnar grains in multilayer columnar crystals had different orientations; while in Scheme 2, they had the same orientation. The simulation result showed that in Scheme 1, the growth of the dendrites, whose orientation had a certain included angle with the direction of temperature gradient, was restrained by the growth of other dendrites whose direction was parallel to the direction of temperature gradient. Moreover, the larger the included angle between the grain orientation and temperature gradient, the earlier the cessation of dendrite growth. The secondary dendrites of dendrites whose grain orientation was parallel to the temperature gradient flourished with increasing included angles between the grain orientation and temperature gradient. In Scheme 2, the greater the included angle between grain orientation and temperature gradient, the easier the dendrites whose orientation showed a certain included angle with temperature gradient inserted between those grew parallel to the temperature gradient, and the better the growth condition thereafter. Some growing dendrites after intercalation were defl ected to the temperature gradient, and the greater the included angle, the lower the defl ection. The morphologies of the competitive growth dendrites obtained through simulation can also be found in metallographs of practical solidification experiments. This implies that the two modes of competitive growth of dendrites characterized in the simulation do exist and frequently appear in practical solidifi cation processes.