摘要
采用基于密度泛函理论(DFT)的第一性原理研究方法,考察了DO_(22)-Al_(3)Nb、L1_(2)-Al_(3)Y和DO_(22)-Al_(3)V等3种金属间化合物的热力学稳定性、电子结构和力学性能。计算结果表明,Al_(3)X(X=Nb,V,Y)金属间化合物的生成焓均为负值,表明三者均为热力学稳定态,且DO_(22)-Al_(3)Nb的生成焓最负,其热力学稳定性最高,L1_(2)-Al_(3)Y和DO_(22)-Al_(3)V次之。杨氏模量E和剪切模量G由大到小排序为DO_(22)-Al_(3)Nb>DO_(22)-Al_(3)V>L1_(2)-Al_(3)Y,可见三者中DO_(22)-Al_(3)Nb强度较高。体模量(B)和剪切模量(G)的比值B/G可用以预测延展性,B/G值排序为DO_(22)-Al_(3)V>DO_(22)-Al_(3)Nb>L1_(2)-Al_(3)Y,可知三者中DO_(22)-Al_(3)V延展性较好。各向异性指数A^(U)的排序为DO_(22)-Al_(3)V>L1_(2)-Al_(3)Y>DO_(22)-Al_(3)Nb。根据电荷密度差分(EDD)和分波态密度(PDOS),考察了三者的原子间成键情况。Al原子倾向于失去电子,而V、Y、Nb原子倾向于得到电子。Al-3s3p轨道和V-3d、Y-4d、Nb-4d轨道的价电子具有强烈的杂化作用,所形成的Al-V、Al-Y和Al-Nb键具有显著的共价特征。
Thermodynamie stability,electronie strueture and mechanical properties of DO_(22)-Al_(3)Nb,L1_(2)-Al;Y and DO_(22)-Al_(3)V intermetallic compounds were investigated by adopting density functional theory(DFT)calculations.The result reveal that formation enthalpies(ΔE_(f))of Al_(3)X(X=Nb,V,Y)are all negative,indicating thermody-namically stable state of compounds.The ΔE_(f) value of DO_(22)-Al_(3)Nb is the most negative,confirming the highest thermodynamic stability,which is sequentially followed by L1_(2)-Al_(3)Y and DO_(22)-Al_(3)V.The Young's modulus E and shear modulus G are ranked as DO_(22)-Al_(3)Nb>DO_(22)-Al;V>L1_(2)-Alg Y,proving the highest strength of DO_(22)-Al_(3)Nb.The ratio of bulk modulus and shear modulus B/G can be utilized to predict the ductility,which are queued as DO_(22)-Al_(3)V>DO_(22)-Al_(3)Nb>L1_(2)-Al_(3)Y,demonstrating the desirable ductility of Al_(3)V.The order of ani-sotropy index A^(U) is DO_(22)-Al_(3)V>L1_(2)-Al_(3)Y>DO_(22)-Als Nb.The interatomic bonding mechanism is clarified ac-cording to the electron density difference(EDD)and partial density of states(PDOS).The result shows that Al at-oms have a tendency to charge donors,while V,Y,Nb atoms tend to be charge acceptors.Strong hybridization exists between valence electrons of Al-3s3p orbital and V-3d,Y-4d or Nb-4d orbital,and formed Al-V,A-Y and Al-Nb bonds have remarkable covalent characteristics.
作者
郑文龙
李健
邓菁玉
张鑫鑫
李宁
吕祥鸿
王晨
Zheng Wenlong;Li Jian;Deng Jingyu;Zhang Xinxin;Li Ning;Lu Xianghong;Wang Chen(School of Materials Science and Engineering,Xi'an Shiyou University;School of New Energy,Xi'an Shiyou University)
出处
《特种铸造及有色合金》
CAS
北大核心
2023年第3期336-342,共7页
Special Casting & Nonferrous Alloys
基金
西安交通大学金属材料强度国家重点实验室开放课题资助项目(20210305)。
