FRACTURE-BEHAVIOR IN 6061-AL-ALLOY MATRIX COMPOSITES WITH DIFFERENT REINFORCEMENTS

The effect of reinforcement size and volume fraction on fracture tough ness in powder metallurgy (P/M)- processed 6061Al alloy matrix composi tes with different kinds of reinforcements (Si3N4 whiskers, and SiC pa rticles) are analyzed. The acoustic emission (AE) activities has also been investigated during three point bending fracture toughness test. Comparing rile fracture toughness results in MMCs containing different volume fractions (V-f) of whiskers and particles show higher fracture toughness in materials with lower V-f. On the other hand, the fractur e behavior in 10 percent reinforced composites regardless of the type of reinforcement, particle or whisker, is ductile fracture,but it is s emi-brittle in the case of 30 percent reinforced materials. Regarding re amplitude and the number of AE events during three point bending fr acture toughness test, 30 percent reinforced materials with brittle fr acture mode show very high amplitude signals with less number of event s in the onset of plastic deformation. 10 percent reinforced composite s with a ductile mode fracture show lower AE amplitude and higher numb er of events. Totally, it kind of interaction between the different pa rameters like volume fraction, reinforcement type and reinforcement si ze on the fracture behavior of 6061 Al alloy matrix composites are obs erved and discussed.