超高强Al-Gd-Ni-Co纳米结构铝合金的增韧机制研究

The development of high performance nanostructured aluminum alloys with both high strength and large tensile plasticity will promote their application in aerospace, rail transit, car, etc. However, the ductility of nanostructured aluminum alloys needs to be further improved and the toughening mechanism is still unclear. We have recently developed a super-high strength nanostructured Al-Gd-Ni-Co alloy with compressive yield strength as high as 1700 MPa. In this research project, in order to produce high strength (1GPa) aluminum alloy with large tensile plasticity, two methods will be used to improve the ductility by developing more volume fraction of ductile phases and adding coarse grained ductile phase in the developed super-high strength Al-Gd-Ni-Co alloy. This research project will focus on the micro crack origination in the nanoscale intermetallics and crack propagation under high stress, as well as the confined effect of the ductile phases on the nanoscale intermetallics under tensile stress. The outcome of this research project is expected to have technique guidance in the field of high performance aluminum alloys which enhances their applications, and potentially leads to improvement in understanding the strengthening and toughening mechanisms in high performance aluminum alloys.

开发兼具高强度和良好拉伸塑性的纳米结构铝合金，将对促进高性能铝合金在航空航天、轨道交通和汽车等领域的应用产生积极作用，但是纳米结构铝合金的塑性和增韧机制还有待于进一步提高和阐明。申请者在前期研究中制备出了超高强度的Al-Gd-Ni-Co纳米结构铝合金，压缩屈服强度达到了1700 MPa。本项目拟以超高强Al-Gd-Ni-Co纳米结构铝合金为对象，通过调控基体铝的比例和导入韧性粗晶相获得双尺度结构两种途径，来提高超高强度纳米结构铝合金的韧性，制备具有高强度（1GPa）和良好拉伸塑性的铝合金，重点从原子尺度揭示高应力下纳米化合物中裂纹的萌生和扩展机制，并阐明拉伸条件下基体铝和韧性粗晶相对纳米化合物的限制效应。本项目可为研制高性能铝合金材料提供技术指导，促进高性能铝合金的应用，同时丰富铝合金在高应力条件下的强韧化理论。

高强铝合金具有较高强度、高比强度和良好的摩擦磨损性能，在航空航天、交通运输等领域有着良好的应用前景。项目的主要研究内容为：超高强度Al-Gd-Ni-Co纳米结构铝合金的致密化、烧结行为和晶化机制研究；超高强度Al-Gd-Ni-Co纳米结构铝合金的微观组织调控和力学性能研究；超高强纳米结构铝合金在拉应力下的强韧化机理和变形机制研究。重要进展包括：通过在过冷液体区域内热压非晶态合金粉末，获得了压力对Al84Ni7Gd6Co3非晶态粉末在烧结过程中的致密化和烧结机制的影响，得出不同压力下Al84Ni7Gd6Co3非晶态粉末在烧结过程中的晶化行为；获得了超高强度Al-Gd-Ni-Co纳米结构铝合金的粉末界面处的致密化行为；通过研究超高强Al-Gd-Ni-Co纳米结构铝合金和韧性α-铝基体，建立了各相体积分数和热挤压工艺参数对组织和性能的影响规律；分析了不同类型、尺度和体积分数的韧性粗晶相的导入与纳米结构区域的相互影响规律，建立了双尺度结构的组织和力学性能的关系，获得了双尺度结构的调控对纳米结构铝合金强度和塑性的影响规律，获得强度显著提升并且保持良好塑性的铝基材料，其拉伸强度接近1000 MPa。本项目成果为采用粉末冶金工艺制备高性能特别是高强度铝合金和铝基材料提供了理论依据和关键技术，深化了对超高强度纳米结构铝合金的强韧化机理的认识。