采用第一性原理平面波赝势方法,计算Al-Zn-Mg-Cu系高强铝合金主要中间相Al2 Cu,Al2 CuMg和MgZn2的结合能、形成焓、弹性常数及态密度。计算结果表明：3相结合能按MgZn2>Al2 CuMg>Al2 Cu顺序递减；形成焓按MgZn2>Al2 Cu>Al2 CuMg顺序递减；Al2 Cu具有很高的弹性模量,同时具有一定的塑性,可以作为合金的强化相；Al2 CuMg是典型的脆性相,并表现出明显的各向异性,容易诱导产生裂纹；MgZn2具有良好的塑性,同时熔点较低,是合金的主要强化相；3相中均存在离子键的相互作用,提高了结构稳定性；通过适当降低Cu,Mg含量,提高Zn的含量,有利于生成MgZn2相,进一步提高合金的综合性能。
Structural stabilities, mechanical properties and electronic structures of Al2 Cu, Al2 CuMg and MgZn2 intermetallics in Al-Zn-Mg-Cu aluminum alloys were determined from the first-principle calculations by VASP based on the density functional theory. The re-sults show that the cohesive energy ( Ecoh ) decreases in the order MgZn2 > Al2 CuMg > Al2 Cu, whereas the formation enthalpy (ΔH) decreases in the order MgZn2 > Al2 Cu > Al2 CuMg. Al2 Cu can act as a strengthening phase for its ductile and high Young’ s modulus. The Al2 CuMg phase exhibits elastic anisotropy and may act as a crack initiation point. MgZn2 has good plasticity and low melting point, which is the main strengthening phase in the Al-Zn-Mg-Cu aluminum alloys. Metallic bonding mode coexists with a fractional ionic in-teraction in Al2 Cu, Al2 CuMg and MgZn2 , and that improves the structural stability. In order to improve the alloys’ performance fur-ther, the generation of MgZn2 phase should be promoted by increasing Zn content while Mg and Cu contents are decreased properly.
参考文献
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%