【摘要】 采用第一原理计算方法,研究了NiTi(B)和NiTi(Nb,B)晶体的形成热焓、结合能、态密度及其电子密度差分。结果表明,在NiTi相基体中,掺杂元素B占4Ti2Ni的形成能力比其在4Ni2Ti中的形成能力更强。对于NiTi(Nb)固溶相,B在相同基体中占据最近邻位比其占据次级邻位更稳定、形成能力更强。态密度和电子密度差分计算表明,B原子与Ti原子、Nb原子形成非常强的共价键,而其与Ni之间成键强度较弱,导致B周围的Ti原子活性降低,从而起到提高Ni/Ti摩尔比,降低NiTiNb合金形状记忆效应的作用。更多还原

【Abstract】 Using first-principles pseudo-potential plane wave method,the formation enthalpy,cohesive energy,density of states and electric density of difference were calculated and analyzed for NiTi(B)and NiTi(Nb,B)phase after boron elements adulterating process.The results show that in NiTi basic crystal,boron atom has much more formation ability in 4Ti2Ni octahedron structure than that in 4Ni2Ti. However,in NiTi(Nb)solid solution crystal,the nearest neighbor site of B-Nb is more stable than the next nearest neighbor site,and the formation ability of the former impurity site is stronger than the next one.The simulation of density of states and electronic density difference shows boron preferring to bonding with Ti atoms and Nb atom,while the bond strength of B-Ni is weak.Such bonding process results in the action of Ti atoms decreasing and the ratio of Ni/Ti increasing,deteriorating the properties of NiTiNb alloy by boron impurity.更多还原