【作者】 邹毅；

【导师】 何德坪；

【作者基本信息】 东南大学 ， 材料加工工程， 2004， 硕士

【摘要】 以多样化孔隙(通孔,闭孔)为特征的超轻型金属结构实现了结构材料的轻质多功能化,从而成为前沿热点材料之一。以往研究的泡沫纯铝及高比强铝合金,其固态孔结构都是多边形孔高孔隙率。为了满足高速运动高技术领域对更高强度的需求,新型球形孔低孔隙率泡沫铝合金刚成为前沿研究的新方向。本文采用位移传感计算机系统,实时连续精确测量了铝合金熔体泡沫界面位移H随时间t变化的H-t曲线,以及熔体泡沫液态孔隙率Pl随时间t变化的Pl-t曲线。研究了铝合金熔体泡沫化过程中,熔体泡沫球形孔的生长及控制规律,并发现球形泡沫与孔隙率Ps,孔径ds及气泡壁厚δs有明确一致的对应关系。控制合适的发泡剂、泡沫化过程及凝固过程,确保球形泡沫生长,就可以获得制备新型球形孔低孔隙率泡沫铝合金的新途径。采用计算机图像分析技术测量了泡沫铝合金气泡直径ds和厚度δs,研究了泡沫铝合金孔隙率Ps与气泡形状Ss、气泡直径ds和厚度δs的关系。新型泡沫铝合金其孔结构的典型特征为:低孔隙率(Ps=65%~80%),Ss为球形或类球形,ds小于2mm,δs大于2mm,。孔隙率大于63%的泡沫铝合金,其与水的比密度小于1,具有轻质性能。通过单向压缩实验,得到了泡沫铝合金的应力-应变曲线,并将球形孔低孔隙率泡沫铝合金与多边形孔高孔隙率泡沫铝合金对比,前者的压缩屈服强度是后者的3~7倍,而吸能能力是后者的3倍左右。更多还原

【Abstract】 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.更多还原