泡沫铝三明治预制坯变形行为及复杂结构制备

Deformation Behavior of Aluminium Foam Sandwich Precursor and Preparation of Complex Structure

利用粉末包套轧制法制备出泡沫铝三明治预制坯,通过室温与高温拉伸实验,研究了三明治预制坯的变形行为;采用冲压成形技术进行了三明治预制坯的成形试验,评价了其成形性能;在高温条件下进行了三明治预制坯的发泡实验,利用光学金相对泡沫铝三明治的微观结构进行了观察,并对孔隙特征进行了计算。结果显示,三明治预制坯既是温度敏感型材料也是速率敏感型材料,在450℃/0.001 s-1的条件下表现出较好的变形性能,其峰值应力与延伸率分别为22.1 MPa和23.8%;与室温条件相比,三明治预制坯在450℃条件下的热冲压成形精度更高,型面弧高达27.1 mm;高温发泡后制备出泡沫铝三明治弧面结构和曲面结构,证实了该工艺路线的可行性,其面板与芯板之间形成了冶金结合,且芯板的孔隙率达78%,平均孔径为3.5 mm,孔壁的微观组织为树枝状α铝和共晶相α＋Si组成。

Aluminium foam sandwich precursor was prepared by powder pack rolling. The deformation behaviors of aluminium foam sandwich precursor were investigated by tensile test under room temperature and high temperature. The shaping properties of aluminium foam sandwich precursor were evaluated by stamping test. The foaming tests of sandwich precursor were carried out with high temperature. The microstructure of aluminium foam sandwich was observed by optical microscope,and the parameter of aluminium foam sandwich was measured. The results showed that aluminium foam sandwich precursor was not only sensitive to temperature but also sensitive to rate. Under 450 ℃/0. 001 s-1,sandwich precursor had better forming properties,and the peak strength and elongation reached22. 1 MPa and 23. 8%,respectively. The forming precision of hot stamping was higher at 450 ℃ than that at room temperature,and the height of arc reached 27. 1 mm. After foaming,the aluminium foam sandwiches were prepared with cambered face and curved face,which demonstrated the route was feasible. The metallurgy bonding between face sheet and core sheet of aluminium foam sandwich has formed. The porosity of core sheet reached 78%,and the average cell diameter was 3. 5 mm. The microstructure of cell wall was composed of dendritic α aluminium and eutectic phase α ＋ Si.