( 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082)
摘 要: 采用第一原理贗勢平面波方法研究了NiAl-X(X為3d過渡金屬)合金體系的幾何與電子結(jié)構(gòu)。通過合金形成能的計算與分析發(fā)現(xiàn)：合金化元素的外層價電子數(shù)對其在B2-NiAl中的占位有非常明顯的影響，低價電子數(shù)的前過渡金屬Sc、Ti、V與后過渡金屬Zn主要占據(jù)Al原子位，具有未滿d殼層高價電子數(shù)的Mn、Fe、Co則主要占據(jù)Ni原子位，而含有半滿或滿d殼層的Cr與Cu，則既可占據(jù)Ni原子位也可占據(jù)Al原子位，但傾向于占據(jù)Ni原子位。隨著合金化元素外層價電子數(shù)的增加，3d過渡金屬優(yōu)先占據(jù)Ni原子位的趨勢增大，至Mn時達(dá)到最大，然后隨著價電子數(shù)的進(jìn)一步增加，這種趨勢逐漸減小。通過對這些合金化元素價電子態(tài)密度圖的變化，說明3d過渡金屬在B2-NiAl中的占位優(yōu)先趨勢。
關(guān)鍵字: B2-NiAl；電子結(jié)構(gòu)；贗勢平面波方法；占位
substitution of 3d transition metal elements
in NiAl intermetallic compound
ZHENG Cai-xing, HAN Shao-chang
（ School of Materials Science and Engineering,
Hunan University, Changsha 410082, China）
Abstract: Site substitutions of 3d transition metal(TM) elements in NiAl intermetallic compound were investigated with the first principle methods based on plane-wave pseudopotential theory. By calculating the formation energy of NiAl alloyed by X element, the site preference were investigated. The results show that the former and later TM elements with low valence electron numbers of Sc, V, Ti and Zn mainly substitute for the Al site in NiAl. The high valence electron numbers elements with un-filled d-shell, e.g. Mn, Fe and Co, primarily substitute for the Ni site in NiAl. The elements with semi-filled or filled d-shell such as Cr and Cu can substitute for either the Ni site or the Al site in NiAl, but preferentially tend to the Ni site. And with the increase of valence electrons in the outer shells in 3d TM, the site preference to substitute for the Ni site increases before Mn and then decreases after Mn. From above results, a reasonable explanation has been given on the analysis basis of the states density of valence electrons of these 3d TM elements in NiAl.
Key words: B2-NiAl intermetallic compound; electronic structure; plane-wave pseudopotential method; site substitution
