Study the Plastic Deformation Mechanism and Thermal Stability of Ultra-strong /ductile Nano-dual-phase Alloys

Description

In the study of structural metallic materials, high strength and large plasticity are always pursuit of the goal. Plenty of strategies were developed to increase the strength of the materials, yet substantially by scarifying the plasticity. In the recent decades, some approaches such as nanotwinning, gradient nanostructuring, dislocation engineering, and nanoparticals precipitation, were able to provide high strength and good plasticity simultaneously. However, the strength increase still has limitations, i.e., it is very difficult to reach to or exceed the metallic glass (MG) regime ofE/50(Eis the Young's modulus of a material) while maintain the plasticity.We recently developed an Mg-based ultra-high strength material, which has an in-situ formed amorphous-nanocrystalline nanostructure, exhibits theoretical strength of 3.3 GPa without sample size effect at room temperature. The related work has been published in Nature. However, the large plasticity occurs only for the samples with the size (diameter) of smaller than 700 nm.In the recent study, we discovered a new kind of ultra-strong NDP-GC nanostructure which would have large plasticity without any size effect. Further investigations on the plastic deformation mechanisms would definitely have profound implications for designing materials with unprecedented mechanical properties. The outcome will pave a novel and effective way to generate NDP-GC alloys with large ductility and ultrahigh strength. Furthermore, we have developed a way to print high specific strength 3D ceramics recently, and the related work has been published in Science Advances. Therefore, it is promising to fabricate 3D printed NDPGC with ultrahigh strength and large plasticity. Our endeavors would facilitate industrial applications in high strength MEMS devices10, surface coatings with high wear resistance, thermal stability and 3D printed microstructures, benefits to fundamental research on materials engineering and the whole society.To improve understanding of the mechanisms for the plastic deformation of NDP-GC nanostructure, the proposed research will be composed of 4 tasks: (1) Study the microstructure generation of Al-based NDP-GC produced by physical vapor deposition with different deposition parameters and comparatively study the mechanical behaviors of the NDP-GC; (2) Study the respective microstructure evolution in the two phases (crystalline phase and amorphous phase) during plastic deformation and the interaction of crystalline phase and amorphous phase in the NDP-GC during plastic deformation; (3) Study the thermal stability of the NDP-GC; (4) Potential 3D printing application of the NDP-GC.