Alumina Particulate Reinforced 7000 Series Composites 930181

A family of metal matrix composites comprised of 7000 series alloys reinforced with aluminum oxide particulate is under development. The matrices include the high strength 7050, 7075 and 7178 alloys as well as 7005. The reinforcement level in the composites varies between 10 and 20 volume percent (14 and 27 weight percent). The particulate is carefully graded aluminum oxide powder ranging in size from 10 to 21 microns. The powders were introduced into the aluminum matrix using ingot metallurgy processing and then DC cast into 178 mm diameter billet. The billet was extruded into bars, heat treated and the mechanical properties evaluated. Elastic modulii in all composites increased with the volume fraction of reinforcement. Uniaxial yield and tensile strengths in excess of 590 MPa and 660 MPa respectively were measured in the 7075 composites. Fatigue strengths of 7005 composites are shown as a function of volume fraction and loading conditions. The stress corrosion cracking response behavior of reinforced 7005 is also discussed.