Research On Dimensional Stability Of The Submicron Al₂o_3p/al Composite

Nine sub-micron Al₂O_3p/Al-Cu-Mg and Al₂O_3p/Al-Mg-Si composites which have different alloy content were prepared by the methed of pressure infiltration. Using brinell hardness (HBS), hot and cold cycle real-time detection, transmission electron microscopy(TEM),tensile test to analysis the aging organizations of those 30vol.% -0.15μm-Al₂O_3p/Al composite, and the impact mechanism of alloy elements on the dimensional stability of composites.For Al₂O_3p/Al-Cu-Mg composites, the dimensional stability of composites were greatly improved after cycles process. With the increasing content of Cu element, the precipitation in composites transformed gradually from a single S 'phase to S' phase and ?? phase, the tensile strength frist increased and then decreased, but the micro-yield strength always increased. The Al₂O_3p/Al-6.5Cu-Mg composite had the best dimensional under no load because of few dislocation and less precipitation. When Mg element content is in the range of 1.2 to 2.0, the Al₂O_3p/Al-Cu-Mg composites had a higher tensile strength and micro-yield strength. This was because high or low Mg elements content of composites had inhibition on aging.On no-load conditions, Too high or too low Mg element would increase the dynamic dimensional stability, lower(△|-)value.According to precipitation conditions of different element content sub-micron Al₂O_3p/Al-Cu-Mg composites. the matrix alloy was designed to meet the basic requirements. When the matrix alloy Cu/Mg atomic ratio of submicron Al₂O_3p/Al-Cu-Mg composite was of 1.8 to 2.3 or 4.3 above, the Al₂O_3p/Al-Cu-Mg composites had the most excellent dimensional stability characteristics.For sub-micron Al₂O_3p/Al-Mg-Si composites, sub-micron Al₂O_3p/6061Al composite showed less precipitation and few dislocation . its tensile strength, hardness and yield strength of micro-elements were higher than the low Mg and high Mg composites.On no load conditions, the sub-micron Al₂O_3p/6061Al composite had the lowest(△|-)value. After T6+TCC treatment process, the precipitate and dislocation in matrix alloy of sub-micron Al₂O_3p/Al-Mg-Si composites would reduced, so the dynamic dimensional stability of the composites was greatly improved.