Mo2ScAlC2的力学行为、键合性质和缺陷过程：一种新的有序MAX相
Mechanical behavior, bonding nature, and defect processes of Mo2ScAlC2: a new ordered MAX phase
摘要：
在本研究中，我们采用密度泛函理论计算研究的力学行为，成键性质和缺陷过程的新的有序MAX相Mo 2ScAlC 2。用单晶弹性常数验证了该化合物的机械稳定性。新相Mo 2ScAlC 2预期倾向于沿晶体学b和c轴剪切，当合理的力施加到晶体学a轴时。在<001>单轴应力作用下，Mo 2ScAlC 2材料沿方向的压缩性较好。此外，体积变形应该是更容易在Mo 2ScAlC 2比在同构Mo 2 TiAlC 2。预测Mo 2ScAlC 2以脆性方式表现。由于其更高的德拜温度，Mo 2ScAlC 2预期比Mo 2 TiAlC 2更导热。与Mo 2 TiAlC 2相比，Mo 2ScAlC 2中的交叉滑移钉扎过程应该明显更容易。新的有序MAX相Mo 2ScAlC 2具有强共价键和金属键的混合特征，具有有限的离子性质。Mo 2ScAlC 2中的Mo-C和Mo-Al键比Mo 2 TiAlC 2中的Mo-C和Mo-Al键更共价。与Mo 2 TiAlC 2中的类似键Ti-C相比，Sc-C键的共价水平稍低。由于其降低的硬度，与Mo 2 TiAlC 2相比，Mo 2ScAlC 2应该更软并且更容易加工。新化合物的费米面拓扑结构主要是由于低色散的Mo 4d类带形成的。本征缺陷过程表明，在Mo 2ScAlC 2的辐射耐受性的水平是不高的其他MAX相，如Ti 3AlC 2。
英文摘要：
In the present study we employed density functional theory calculations to investigate the mechanical behavior, bonding nature and defect processes of the new ordered MAX phase Mo2ScAlC2. The mechanical stability of the compound is verified with its single crystal elastic constants. The new phase Mo2ScAlC2 is anticipated to be prone to shear along the crystallographic b and c axes, when a rational force is applied to the crystallographic a axis. The compressibility along the <001> direction under uniaxial stress is expected to be easier in Mo2ScAlC2. Additionally, the volume deformation should be easier in Mo2ScAlC2 than in the isostructural Mo2TiAlC2. Mo2ScAlC2 is predicted to behave in a brittle manner. Due to its higher Debye temperature, Mo2ScAlC2 is expected to be thermally more conductive than Mo2TiAlC2. The cross-slip pinning procedure should be significantly easier in Mo2ScAlC2 as compared to Mo2TiAlC2. The new ordered MAX phase Mo2ScAlC2 has a mixed character of strong covalent and metallic bonding with limited ionic nature. Both Mo-C and Mo-Al bonds are expected to be more covalent in Mo2ScAlC2 than those of Mo2TiAlC2. the level of covalency of Sc-C bond is somewhat low compared to a similar bond Ti-C in Mo2TiAlC2. Due to its reduced hardness, Mo2ScAlC2 should be softer and more easily machinable compared to Mo2TiAlC2. Fermi surface topology of the new compound is formed mainly due to the low-dispersive Mo 4d-like bands. The intrinsic defect processes reveal that the level of radiation tolerance in Mo2ScAlC2 is not as high as in other MAX phases such as Ti3AlC2.
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