Study On A New Type Of Spherical Pore Al Alloy Foam With Low Porosity And High Strength

The Ultra Light Metal Structure with various kinds of pores(open, close) realizes the lightness and multifunction of structural material.The Al alloy foam with high specific strength studied in the past few years has polygonal pores and high porosity. In order to meet the requirement of higher specific strength for high speed movement and high tech area, a new type of spherical pore Al alloy foam with low porosity becomes a new trend of research work.A computer system for displacement sensor is developed to measure the shifting interface of molten Al alloy foam continuously and accurately, by which the change of porosity of molten Al alloy foam is studied. The H-t curve which expresses the relationship between the displacement of the interface and time, is relevant to the Pl-t curve which expresses the relationship between the porosity of melting Al alloy foam and the time. The growth of spherical bubbles has definite connection with low porosity, small diameter and great thickness of pore. Therefore, the new type of spherical pore Al alloy foam with low porosity can be produced by appropriately choosing the amount of the foaming agent, controlling the foaming time and solidification method to ensure the spherical bubble's growth.The graphic analytic technology aided by computer is used to measure the average diameter and thickness of the pores in the Al alloy foam. The relationships between the porosity Ps of the Al alloy foam and the shape, diameter ds and thickness δs of the pores are studied. The typical characters of the spherical pore Al alloy foam with low porosity are listed as following: Ps between 65% and 80%, ds below 2 mm, δs above 2 mm and spherical pore.The Al alloy foam with low porosity has a density lower than that of water, which forms its light structure. The compressive yielding strength of spherical pore Al alloy foam with low porosity is 3~7 times greater than that of polygonal pore Al alloy foam with high porosity. And the energy absorption capability is increased by 3 times.