摘要
通过分子动力学(MD)模拟方法对Ti_(3)Al合金在定向凝固条件下的生长机理进行系统研究,并通过对比纳米晶(NG)、粗晶(CG)和梯度纳米晶(GNG)合金,研究Ti_(3)Al合金的结构力学性能。结果表明,在凝固过程中Ti_(3)Al相优先生长为等轴晶组织,随后逐渐演变为柱状粒,并最终形成梯度纳米晶结构。此时,晶粒在与凝固方向平行的方向优先生长。此外,研究还发现,相较于NG和CG结构,GNG结构定向凝固合金具有更高的抗拉强度和更好的延展性。GNG结构不仅有效抑制了小晶粒区域的应变局域化和晶粒生长,而且促进了较大晶粒区域的位错形成,从而获得更好的力学性能。
The formation mechanism of Ti_(3)Al alloy during a directional solidification process was systemically investigated by means of molecular dynamics(MD)simulations,and its mechanical behavior was explored by comparing with its nanograined(NG),coarse-grained(CG)and gradient nanograined(GNG)counterparts.It is found that the solidified front forms equiaxed crystals first,then they transform into columnar crystals,and the GNG structure is formed finally.Noticeably,the grains will grow preferentially in the direction parallel to the solidification direction.Besides,it is also found that the directional solidified alloy with the GNG structure has higher tensile strength and better ductility than its NG and CG counterparts.The GNG structure not only suppresses strain localization and grain growth in its small grain regions,but also promotes more cross dislocations in the large grain regions,resulting in a better mechanical performance.
作者
邹鹏飞
李昌
侯兆阳
Jia-yi SUN
高全华
李克凡
王真
Ke-jun DONG
Peng-fei ZOU;Chang LI;Zhao-yang HOU;Jia-yi SUN;Quan-hua GAO;Ke-fan LI;Zhen WANG;Ke-jun DONG(School of Science,Chang’an University,Xi’an 710064,China;Faculty of Natural,Mathematics&Engineering Sciences,King’s College London,London,WC2R 2LS,United Kingdom;School of Engineering,Design and Built Environment,Western Sydney University,Penrith,NSW 2751,Australia)
基金
National Natural Science Foundation of China(No.52201103)
Natural Science Basis Research Plan in Shaanxi Province of China(No.2023JCYB445)
Fundamental Research Funds for the Central Universities of CHD(Nos.300102122201,300102122106)。
关键词
定向凝固
Ti_(3)Al合金
分子动力学模拟
梯度纳米结构
directional solidification
Ti_(3)Al alloy
molecular dynamics simulation
gradient nanograin structure
