寻找硬度达到甚至超过传统金刚石，并且具有高断裂韧性、抗腐蚀、能够导电的新型超硬-超韧材料是长期以来物理和材料科学领域中的重要课题。近年来，人们利用纳米尺寸以及纳米形貌的强化作用，成功合成了硬度比传统金刚石还高的纳米金刚石、立方BN，为结构功能材料的设计开辟了新的思路。过渡金属硼化物和氮化物是超硬材料体系中的重要成员，具有高强度、高稳定性、非绝缘性等重要性质。本项目中，我们主要以纳米过渡金属硼化物和氮化物为研究对象，通过高能球磨以及二级推进压机在高温高压条件下反应，合成具有纳米尺寸/形貌的超硬-超韧纳米晶；通过中子衍射/PDF分析等手段，精修得到纳米尺寸调制的晶格结构信息；利用金刚石对顶砧、deformation-dia型大腔体压机并结合同步辐射X射线衍射技术研究样品的弹性-塑性形变机理；利用透射电子显微镜技术分析微观形变机制，建立结构-性质的基本物理学模型，进一步完善纳米力学理论。

Designing new superhard-ultratough materials with novel/improved performances has been the constant endeavors of the physics and material science communities. Recently, polycrystalline diamond of nanostructures and cubic boron nitride polycrystalline bulks with “ultrafine nanotwins” have been synthesized under high pressure and temperature conditions. Both the nano-structured materials are colorless with much enhanced hardness, thermal stability, yield strength, and fracture toughness compared to that of natural diamonds which provides an effective route for superhard-ultratough material strengthening...Transition metal nitrides/borides have recently attracted considerable interest because of their unique mechanical, electronic and chemical properties for technological applications. Unfortunately, these materials do not even approach the hardness of cubic boron nitride, owing to the partially ionic and the metallic bondings. We propose to improve the mechanical performance of the transition metal nitrides/borides by producing nano scale/ nano-structure grains. The keys to this success are based on ball-milling and high-pressure/high-temperature reactions in which the pressure could suppress the grain growth to micron scale. Neutron Pair Distribution Function（NPDF）will be an effective way to analyze the short-range/ long range disorder of the structure in nano grains, since the B, N elements are light thus weak X-ray scatters. “Diamond Anvil Cell (DAC)” and “Deformation-Dia” incorporated with synchrotron X ray diffraction will be used to derive the equation of state and the constitutive law of the single phase nano crystalline materials. The after deformed samples will be further examined by TEM characterizations. By analyzing the relations of nano structure-mechanical performances-micro defects characterization, the nano mechanism in the non-metallic superhard materials will be further developed and better understood.