基于第一性原理研究 M(M =Ti,V,Cr,Mn,Co和Ni)掺杂α-Fe(N)的结合能、电子结构及力学性能。计算结果表明,Ti和V优先占据晶胞的顶角位置,Cr和Mn优先占据晶胞的体心位置,Co和Ni与N不相邻时结构最稳定。Ti与V的掺杂加强了晶胞的稳定性,Cr, Mn与Ni的掺杂削弱了晶胞的稳定性,Co的掺杂不影响晶胞的稳定性。这些过渡金属在α-Fe晶胞中均存在金属键和离子键的共同作用,成键轨道主要来自 M 3d, Fe4s3p3d与N2p。与纯α-Fe体系相比,掺杂体系刚性均变强,经计算可得α-Fe(N)-V体系的弹性模量 E 、剪切模量 G 和体积模量 B 均为最大值,即掺杂V可显著提高材料的力学性能,V是最有效的固氮元素,与高氮钢冶炼的实验结果相吻合。
The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles method.The calculated results show that the dopings of Ti,V,Cr and Co improve the stability ofα-Fe（N）,and the stability ofα-Fe（N）is slightly weakened by Mn and Ni,and the doping of Mg is disadvantageous.For Ti,V,Cr and Mn dopedα-Fe（N）systems in which the doping metals are on the left side of Fe in the element periodic table andα-Fe（N）systems doped by Co and Ni on the right side of Fe,their corresponding cohesive forces decrease with decreasing atomic radius of the doping species.The obvious interaction exists among M3 d,Fe4s3p3d and N2 p.In these doping systems,metal atoms lose electrons,while N gains electrons.Dopings of Ti,V,Cr and Mn inα-Fe（N）strengthen the interaction between N and the surrounding metals,and it is not apparent for the dopings of Co,Ni and Mg.Elastic calculations of Fe15 MN systems show that,except for the Fe15 MgN system,shear modulus G and Young modulus E of Fe15 MN systems are improved,and the bulk modulus Bslightly decreases,namely,total elastic properties are enhanced.The magnitude change rule of E reflecting the cohesive force between atoms is consistent with that for the binding energies.
采用蔡司显微镜、扫描电镜等研究了固溶处理对304L不锈钢晶粒长大及力学性能的影响。结果表明:固溶温度越高,晶粒长大速度变快,硬度呈现下降的趋势。保温1 h时,晶粒长大激活能为223.41 k J/mol,硬度下降速率呈现快、慢、快的特点;保温2 h时,晶粒长大激活能为211.09 k J/mol,硬度下降速率呈现逐渐变快的特点。固溶处理后的冲击韧性更好。
