Plastic deformation of cast reinforced metals

To measure the influence of a reinforcement on the flow stress of aluminum and copper based matrices, continuous parallel alumina fiber reinforced composites are produced by pressure-infiltration, and tested in tension/compression along the fiber axis. In this configuration, the matrix strain is relatively uniform in the composite, and the equistrain rule of mixtures, modified to take into account Poisson's ratio effects, can be used to back-calculate the matrix flow stress from that of the composite. Derived matrix in-situ stress-strain curves are presented for cast Dupont FP(TM) and 3M Nextel 610(TM) alumina fiber reinforced aluminum and copper-based matrices. The discussion of results is centered on the question of precision in the measurement of matrix in-situ stress-strain curves, and on the influence of differential contraction between matrix and fiber during cooldown of the composites from processing temperatures.