Effect of gradient structure of Al-Si-Cu-Ni alloy on bending properties
SHI Zhichao1，YAN Biao1,2,3，YAN Pengfei4
（1. School of Materials Science and Engineering, Tongji University, Shanghai 201804, China;2. Suzhou Kailei
Intelligent Equipment Co., Suzhou 215332, China; 3. Shanghai key Laboratory for D&A of Metal functional
Materials, Shanghai 201804, China; 4. Eighth Research Institute of Nuclear Industry, Shanghai 201800, China）
Abstract：Al-Si-Cu-Ni gradient-structured alloys were prepared under different process parameters by varying
the laser power during selective laser melting and forming, and the bending properties were tested under positive
and negative pressure conditions. After optimizing the process parameters, the comprehensive mechanical properties
of the gradient-structured alloys were improved, the microstructures at different locations on the sides were
observed, and the hardness distribution was tested. The results show that the bending properties under positive
pressure conditions are better than those under counterpressure. With the increase of laser power, the microstructure
is gradually coarsened, the precipitation amount of Cu-rich and Ni second phases increases, and the Vickers
hardness and Brinell hardness linearly decrease, which makes the alloy samples produce a gradient structure. The
bending strength and fracture displacement of the gradient-structured alloys prepared under the optimal process
parameters under positive pressure can reach (838±22) MPa and (0.93±0.04) mm, which are significantly higher
than those of the homogeneous structure alloys ((767±24) MPa, (0.85±0.03) mm), indicating that the gradient
structure produces a toughening effect on the alloy materials, which is mainly attributed to the high strength of
the fine-crystalline tissues, good plasticity of the coarse-crystalline tissues, and good plasticity of the coarse-crystalline
tissues. The synergistic effect of the gradient structure on the alloys is mainly attributed to the high
strength of the fine-crystalline tissue and the good plasticity of the coarse-crystalline tissue.
2024, Vol. 34 
