( 1. 湖南大學 材料科學與工程學院，長沙 410082;
2. 廣東醫(yī)學院 第二臨床學院， 東莞 523808)
摘 要: 采用第一原理贗勢平面波方法， 計算幾種合金化元素X(X= Cr、 Mn、 Fe、 Co和Cu)與不同F(xiàn)e含量(0, 3.125％, 4.167％, 6.25%, 摩爾分數(shù)) (NiFe)Al超胞的幾何與電子結構， 并采用如下幾個力學參數(shù)： 彈性常數(shù)C44、 Cauchy壓力參數(shù)(C12-C44)、 彈性模量E和剪切模量G及比值G/B0等， 表征和評判了合金化元素X與不同F(xiàn)e含量對NiAl金屬間化合物延性與硬度的影響。 結果表明： 高濃度(6.25%)合金化雖可提高NiAl晶體的硬度， 但卻導致NiAl延展性降低， 合金化后NiAl硬度增加的次序為： (Ni7Mn)Al8＞(Ni7Co)Al8＞(Ni7Fe)Al8＞(Ni7Cr)Al8＞(Ni7Cu)Al8＞NiAl， 其延性降低次序則與硬度增加次序相反； 隨著Fe含量的升高， NiAl晶體的硬度增加， 但其使硬度增加的上限約為4%， 而隨著Fe含量的降低， NiAl晶體的延性逐步增大， 當Fe含量低到一定程度時， 可改善NiAl晶體的本征脆性。
關鍵字: B2-NiAl； 贗勢平面波方法； 合金化； 彈性模量
（ 1. School of Materials Science and Engineering, Hunan University,
Changsha 410082, China;
2. The Second Clinic School of Guangdong Medical College,
Dongguan 523808, China）
Abstract: Using the first-principles pseudopotential plane-wave methods based on the density functional theory, the geometric and electronic structures of (NiX)Al supercells with different alloying elements X (X=Cr, Mn, Fe, Co and Cu) or different Fe contents, e.g. 0, 3.125%, 4.167% and 6.25%(mole fraction) are calculated. Several mechanical properties parameters such as elastic constant C44, Cauchy pressure parameter (C12-C44), elastic modulus E, the shear modulus G and their ratio G/B0 are used to characterize and assess the effect of alloying element and Fe content on the ductility and hardness of NiAl intermetallic compounds, respectively. The result shows that high addition of alloying element X (6.25%) can not enhance the ductility of NiAl intermetallic compound although it makes the hardness of NiAl improve as following order: NiAl＜(Ni7Cu)Al8＜(Ni7Cr)Al8＜(Ni7Fe)Al8＜(Ni7Co)Al8＜(Ni7Mn)Al8. And the decreasing order of ductility of NiAl induced by alloying element X is opposite to their hardness increasing order. With the increase of Fe content, the hardness of NiAl is elevated. And the upper limit making the hardness of NiAl increase is about 4%. Meanwhile a gradual improvement of the ductility of NiAl is also observed as Fe addition content decreases. From this variation tendency of the ductility of NiAl versus Fe content, a deduction is made. The intrinsic embitterment of NiAl can be restrained if Fe content is enough low.
Key words: B2-NiAl; pseudopotential plane-wave method; alloying; elastic modulus
