点缺陷对L1_2-Al_3Li金属间化合物热力学性能的影响

运用基于第一性原理的平面波赝势法研究了L12-Al3Li金属间化合物中Li原子空位和Al原子反位缺陷对Al3Li热力学性能的影响,结果表明:Al反位缺陷易与周围原子形成局域共价键,使晶体体积增大,而Li空位缺陷却减小了晶体体积.Li空位缺陷使L12-Al3Li的硬度增加,延展性降低,德拜温度值升高.Al反位缺陷降低了晶体的硬度,增加了延展性,降低了德拜温度值.在德拜温度以下,Li空位缺陷减小了L12-Al3Li的热容,而Al反位缺陷使晶体热容增大.晶格畸变对L12-Al3Li晶体的热力学性能有重要影响.

Mechanical and thermal properties of L12 -Al3Li intermetallics with point defects

The effects of Al anti-site and Li vacancy defects on the mechanical and thermal properties of L12 -Al3Li intermetallics compound were investigated on the basis of the first-principle pseudopotential plane-wave method. The results show that the Al anti-site tends to shape the covalent bonds with surrounding atoms which causes the increase in volumes of the crystal, whereas Li vacancy reduces the volume of the corresponding crystal. The Li vacancy slightly improves the hardness , weakens the ductility, and increases the Debye temperature, while Al anti-site distinctly exhibits opposite influence on hardness, ductility and Debye temperature. Under the Debye temperature, the specific heat of L12 -Al3Li decreases weakly with Li vacancy, but it is clearly increased by the Al anti-site. The deformation of volume of corresponding super crystal plays an important role on the change of mechanical and thermal properties of L12 -Al3Li.