FABRICATION AND DAMPING CAPACITY OF CU-ZN-AL MATRIX COMPOSITES PROCESSED BY POWDER-METALLURGY ROUTE

Cu-26.5Zn-4Al (wt.%) alloy (as a matrix) and each of three different F e-based ferromagnetic alloy flakes (as a reinforcing material) were pr ocessed into three different composites via conventional cold compacti on; this was followed by hot isostatic pressing. The sliced sheets of the composites were heat-treated at 1073 K and quenched into ice water to introduce a martensitic structure. The damping capacity and the st orage modulus were measured for three different composites as function s of strain amplitude and frequency. The microstructure of the composi tes was characterized by use of optical microscopy, scanning electron microscopy and scanning transmission electron microscopy in order to e xamine the martensites, the flake morphologies and the interfaces. In all three composites, the loss factor increased from 0.02 (with a stra in of 100 X 10(-6)) to approximately 0.05 (with a strain of 300 x 10(- 6)). In particular, the Fe-Cr flakes/Cu-Zn-Al composites exhibited a m aximum loss factor near a strain of 165 x 10(-6), owing to the damping of the Fe-Cr flakes.