【摘要】 以Ti-Al的3个化合物相(Ti3Al、TiAl和TiAl3)及Ti3Al8Mn为对象,采用密度泛函的赝势平面波法,在优化驰豫的基础上计算其电子结构和弹性模量,系统分析成分对各相电子结构的变化及脆性的影响。结果表明:Al含量逐步增多导致Al2p—Ti3d成键并抑制Ti—Ti键,使共价键以及成键的各向异性增强,因而使合金脆性增大;Mn替代Al位掺杂后,可减少Al—Al共价键,抑制Al2p—Ti3d成键并增强Mn与Ti的3d电子层杂化程度,降低由Al—Al共价键和Al2p—Ti3d杂化键形成所带来的键的空间各向异性和高位错能垒,进而改善合金的室温脆性。更多还原

【Abstract】 Targeted to the three-phases of Ti3Al,TiAl and TiAl3 of Ti-Al and Ti3Al8Mn as well,and tased on the geometry optimization relaxation,the electronic structures and elastic modulus are calculated using the density functional plane wave pseudopotential method,and the effects of composition on the electronic structure of the phases and brittleness have been analyzed.The results show that: the increasing of Al content leads to Al2p—Ti3d bond increase and Ti—Ti bond decrease,which can enhance the anisotropy of covalent bonding and the room temperature brittleness of alloy increase.Since Mn doping in Al can decrease Al—Al covalent bond,inhibit Al2p—Ti3d bonding and enhance Mn and Ti hybrid of 3d,the space anisotropy and high energy barrier caused by Al—Al covalent bond and Al2p—Ti3d hybrid bond reduce,which can improve the room temperature brittleness of TiAl3 alloy.更多还原