A COMPARISON OF 2 NEXTEL-440 FIBER-REINFORCED ALUMINUM COMPOSITES USING ACOUSTIC-EMISSION

The acoustic emission (AE) response and mechanical behaviour of two Ne xtel 440 fibre reinforced aluminium composites were compared. The tota l cumulative AE events were found to occur in two regions. The first r egion occurred at smaller strains and had a large exponential rise in events for the reinforced 6061 composite and few events for the high p urity aluminium matrix composite. The difference was attributed to the alloy constituents of the 6061 aluminium matrix. The events were attr ibuted to a dislocation release mechanism that occurred prior to yield ing of the matrix. In the second region of events in the reinforced 60 61 composite the event rate was constant and continued to failure. The second region of events in the high purity aluminium (HPAL) composite had a steady increase in the event rate until a constant rate was rea ched prior to failure. The events in the reinforced HPAL composite wer e attributed to the fracturing of fibres and the associated plastic de formation of the matrix that accompanies fibre failure. Thus failure i n the materials occurs due to the propagation of fracturing fibres. Th e propagation was rapid in the reinforced 6061 aluminium composite. Th e reinforced HPAL composite had a slower propagation due to the high d uctility of the HPAL.