SiC-Al界面微区异质叠层结构的微纳力学研究

Interface play a critical role for metal matrix composites in the deformation process, however, the difficulty in quantitatively studying the correlation of “interfacial structure-mechanical property” due to its complex and microscopic characters. This project will be based on the previous research that the applicant observed the phenomenon of grain refinement, increased strength and work hardening rate in deformed interfacial micro-region of SiC/Al composite pillar after uniaxial compression. Meanwhile, this project will also be based on the recent reports that the lamella and gradient structures have the potential of achieving both high strength and high ductility. In this project, using magnetron sputtering deposition method, we will introduce a heterogeneous lamella structure with alternating arrangement of coarse-/ultrafine-grained Al in the width-scale of interfacial micro-region in SiC/Al metal matrix composites. Additionally, the single-grained, coarse-grained and ultrafine-grained Al counterparts will be fabricated respectively. In particular, by fabricating corresponding composite pillars and then employing the micro-/nano-mechanics approaches, we will study the correlation of “structural evolution-mechanical property” and then explore the correlation of ultrafine-grains and strength, coarse-grains and ductility, multi-interfaces and interfacial debonding, multi-interfaces and crack-extension in the heterogeneous lamella structure. This project will offer a reference model for structural readjustment in interfacial micro-region of engineering metal matrix composites and a theoretical basis for overcoming the strength-ductility trade-off of metal matrix composites through the structural readjustment.

界面在金属基复合材料形变中扮演着重要角色，但由于其微观性和复杂性给定量研究“界面结构-力学性能”之间的耦合关系带来困难。本项目基于申请人前期的研究发现，即碳化硅（SiC）/铝（Al）复合微柱单轴压缩后界面微区出现晶粒细化及强度和加工硬化率提高的现象，同时基于近来报道的关于叠层、分级结构对材料强度-塑性的调制作用。本项目拟在SiC/Al复合材料界面微区宽度范围内，采用磁控溅射沉积引入粗晶/超细晶排布的异质叠层Al结构，此外作为对比分别引入单晶、粗晶、超细晶Al结构，并制备相应复合微柱，进而利用微纳力学研究其“构型演化-力学性能”的关系，探究界面微区异质叠层结构中超细晶与强度、粗晶与塑性、多界面与界面脱粘、裂纹扩展之间的耦合关系。本研究将为实际的金属基复合材料界面微区的异质叠层调控提供模型参考，为金属基复合材料通过结构调控来解决其强度-塑性失配问题提供理论基础。

界面在金属基复合材料形变中扮演着重要角色，但由于其微观性和复杂性给定量研究“界面结构-力学性能”之间的耦合关系带来困难。本项目基于申请人前期的研究发现，即碳化硅（SiC）/铝（Al）复合微柱单轴压缩后界面微区出现晶粒细化及强度和加工硬化率提高的现象，同时基于近来报道的关于叠层、分级结构对材料强度-塑性的调制作用。本项目在SiC/Al复合材料界面微区宽度范围内，采用磁控溅射沉积引入粗晶/超细晶排布的异质叠层Al结构，并制备相应复合微柱，利用微纳力学研究其“构型演化-力学性能”的关系，探究界面微区异质叠层结构中超细晶与强度、粗晶与塑性、多界面与界面脱粘、裂纹扩展之间的耦合关系，探究界面微区异质叠层结构中超细晶与强度、粗晶与塑性、多界面与界面脱粘、裂纹扩展之间的耦合关系。本项目获得了如下进展：1) 通过磁控溅射的参数调控成功在SiC/Al界面微区内进行了纳米晶、超细晶、细精的多尺度结构调控，而且验证了小尺度提供强度，大尺度贡献塑性的预测；2) 通过在SiC/Al界面微区多尺度的结构调控发现Al非晶、纳米晶、超细晶之间的多尺度组合为本研究提供了更大的可变空间，获得了超预期的高强、高塑性，30%塑性变形中最大抗压强度高达1.7 GPa，且SiC/Al界面结合良好，并未见界面脱沾与裂纹扩展出现，探究了其高强、高塑性的机制；3) 拓展性开展了室温下SiC/Al小尺度的累积梯度形变，成功在SiC/Al界面微区内构筑了纳米晶、超细晶、细精的多尺度结构，大幅提高了强度，并探究了其结构与演变的机制。.本研究将为实际的金属基复合材料界面微区的异质叠层调控提供模型参考，为金属基复合材料通过结构调控来解决其强度-塑性失配问题提供理论基础。