|
|
|
| Preparation and mechanical properties of a 7075/TC4 composite material |
| DONG Zhiyan，ZHAO Haidong，YANG Chao，ZHANG Weiwen，WANG Zhi |
| （National Engineering Research Center for Near-Net-Shape Forming of Metallic Materials, South China
University of Technology, Guangzhou 510640, China） |
|
|
|
|
Abstract With the rapid development of aerospace and rail transit, single metal material is difficult to meet the
requirements of light weight and high strength. Heterogeneous composite materials combined with two or more
metal materials can obtain a good combination of strength and toughness. 7075 aluminum alloy has high strength
and low density, and TC4 titanium alloy is the most widely used titanium alloy with both strength and toughness.
Therefore, 7075 aluminum alloy and TC4 titanium alloy are combined to obtain bimetallic composites with excel‐
lent properties.In this paper, TC4 titanium alloy honeycomb topological structure preform was prepared by Selec‐
tive Laser Melting technology, and 7075 aluminum alloy melt was infiltrated at 700/750/800 °C by vacuum pres‐
sure infiltration to obtain 7075/TC4 composites. The area of 7075 aluminum alloy in 7075/TC4 composites is main‐
ly composed of fcc-Al, Al3Fe and MgZn2. The region of TC4 titanium alloy is mainly composed of lamellar α phase
and β phase. The interface layer is mainly composed of Al3Ti, and its thickness increases from 6 μm at 700 °C to
about 300 μm at 800 °C. When the infiltration temperature is 750 °C, the properties of the composites are the best,
and the yield strength, compressive strength and fracture strain are (755±5) MPa, (1 136±12) MPa and 23%±1.5%,
respectively. The fracture behavior of the composite material is as follows: the crack initiates at the grain boundary
of the aluminum alloy region. With the increase of load, the cracks in the aluminum alloy area expand, and the
cracks initiate at the defects of the interface and the titanium alloy area. With the further increase of the load, cracks in the aluminum alloy region expand to the interface, and connect with the cracks in the interface and the ti‐
tanium alloy structure region, resulting in material failure. At different infiltration temperatures, the phase composi‐
tion of the composite 7075 aluminum alloy region, TC4 titanium alloy region and interface region is similar. How‐
ever, the thickness of the interface layer increases with the increase of infiltration temperature. With the increase of
infiltration temperature, the compressive strength and compressive plasticity of the composites first increase and
then decrease, and reach the best at 750 °C. The grain boundary second phase, infiltration defects and SLM defects
have adverse effects on the properties of the composites.the
|
|
Received: 25 October 2022
|
|
Corresponding Authors:
王 智（1982—），男，博士，教授，主要研究方向为3D打印金属材料，铝合金及其复合材料，钛合金等。
|
|
|
|
|
|
|
2023, Vol. 33 
