Fabrication And Properties Of Amorphous Al-Based Metal Foams

In this paper, the Al-Cu-Ti amorphous powders were obtained by high-energy ball milling. NaCl was used as the spaceholder. The amorphous Al-based metal foams with more than 65% porosity have been fabricated by a spark plasma sintering(SPS) process. The microstructure and compressive property of the amorphous Al-Cu-Ti metal foams were systematically investigated under different sintering factors, the percentage and size of NaCl. Besides, the porosity and mechanical behavior of the foams were characterized.The almost fully amorphous Al-Cu-Ti alloy powders were obtained after 30 h mechanical milling, where the TiH2 phase was also observed, but TiH2 was thermally decomposed during SPS. The sintering temperature, pressure and dwell time improved the crystallization, densification and adhesion of the amorphous Al-Cu-Ti alloy powders.Static compression properties of amorphous Al-based metal foams were tested with 5×10-4s-1. Serrated features were observed in the stress-strain curves for compression. It also showed two obvious stages of deformation and pore slumping platform with an unconspicuous densification platform observed. With the increases of temperature, pressure and dwell time, the densification platform and the serrated area increased. The fracture mechanism is brittle fracture. The cracks were observed around holes because of the strain concentration and nonuniform compressure.The percentage and size of NaCl are the key factors in mechanical properties of amorphous Al-based metal foams. Under uniform stress condition, the compressive strength is consistent with the decrease of porosity. The highest compressive strength is 28.3MPa with porosity 50%. The crystallization of amorphous Al-based metal foams increases with the higher percentage or bigger size of NaCl because of the high current density. And the pore size was in accordance with the increase of percentage or size of NaCl powders. However, the NaCl phase was observed with smaller size of NaCl.The present research will lay a solid foundation to the study of lightweight foam amorphous.