Investigations into the Phase Segregation, Formation of nanostructure with a high thermal stability and origin of the hardness enhancement in Superhard Nanocomposites consisting of a stable, hard, transition metal nitride and Si3N4 or BN as interfacial ph

研究由稳定的硬质过渡金属氮化物和 Si3N4 或 BN 作为界面相组成的超硬纳米复合材料中的相分离、具有高热稳定性的纳米结构的形成以及硬度增强的起源

• 批准号: 52425726
• 负责人: Professor Dr. Stan Veprek
• 金额: --
• 依托单位: Fakultät für Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/52425726?language=en
• 关键词: Investigations; into; Phase; Segregation; Formation

Theoretical investigation into the phase stability and segregation in nitride systems, such as Ti-Si-N and Ti-B-N, Ti-Al-N, Cr-Al-N, which form superhard nanocomposites and coatings. Ab initio DFT calculations will provide the lattice stability of metastable phases and the interaction parameters which will be used to calculate the Gibbs free energy of the mixed stoichiometric nitrides in wide range of nitrogen pressure and temperature that are relevant for the deposition and application of the nanocomposites. If, as expected, these calculations will yield the chemical spinodal, the effect of the interfacial energy will be considered in order to elucidate if, and under which conditions the system will remain also coherently spinodal. Later on, the calculations will be extended to more complex systems, such as nc-(TiAl)N/a- Si3N4, nc-(AlCr)N/a-Si3N4, and - if the time will allow us - also to selected oxide systems which may be of great interests for industrial applications. The reliability of the results will be tested by calculating the materials parameters for pure substances, such as TiN, Si3N4 ... (energy of formation, lattice constant, elastic moduli, decohesion energy) and their comparison with available experimental data. In order to understand the origin of the hardness enhancement, the strain - stress curves will be calculated using the ab initio DFT method, and than used in a construction of realistic mechanical models of both, the nanocomposites and of the recently prepared heterostructures.

对构成超硬纳米复合材料和涂层的氮化物体系，如Ti-Si-N和Ti-B-N、Ti-Al-N、Cr-Al-N中的相稳定性和偏析进行了理论研究。从头算DFT计算将提供亚稳相的晶格稳定性和相互作用参数，这些参数将用于计算混合化学计量氮化物在与纳米复合材料的沉积和应用相关的宽范围的氮气压力和温度下的吉布斯自由能。如果，正如预期的那样，这些计算将产生化学旋节线，界面能的影响将被考虑，以阐明如果，以及在何种条件下，系统将保持也相干旋节线。稍后，计算将扩展到更复杂的系统，如nc-（TiAl）N/a-Si 3 N4，nc-（AlCr）N/a-Si 3 N4，如果时间允许的话，还将扩展到可能对工业应用有重大意义的选定氧化物系统。通过计算纯物质的材料参数，如TiN，Si 3 N4...（形成能，晶格常数，弹性模量，消粘能），并与现有的实验数据进行比较。为了理解硬度增强的起源，将使用从头算DFT方法计算应变-应力曲线，然后用于构建纳米复合材料和最近制备的异质结构的现实力学模型。