Abstract:
Process control is becoming increasingly importan to the high performance applications of aluminum mete matrix composites. Most processing methods of mete matrix composites introduce a degree of anisatropy which results in the directional dependence of material properties Anisotropy in these composites is rabidly due to the preferred alignment of the matrix crystallites and/or the alignment of the reinforcement. Thus, comparing measured an/ theoretical anisotropy parameters for perfectly aligned fiber and for texture in the matrix can determine the contributor to anisotropy in the composite material. The anisotropy of aluminum alloys reinforced with up to 20 volume % silicon carbide or alumina particles was investigated using ultrasonic velocity measurements. The measurements indicate the these composites are transversely isotropic and thus their elastic properties can be described by the five independent elastic constants C11, C22, C44, C12, and C23. The results also show that there is a constant ratio of compressional and shear constants which exhibits a strong dependence on sources of anisotropy in the composite and can distinguish between matrix and reinforcement textures. This approach give promise to the use of ultrasonic velocity measurements for the control of texture in the manufacturing of metal matrix composites.
This research is sponsored by the Army Research Office under contract No. DAAH04-95-1-0566.
Source: Proceedings of the 'NDE applied to Process Control of Composite Fabrication' - Conference, 1-2 Oct 1996 St. Louis, Missouri. Publisher and Organizer: Nondestructive Testing Information Analysis Center (NTIAC) Texas Research Institute Austin, Inc. Austin, Texas [http://www.ntiac.com] [Buying the Proceedings]
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