FRACTURE TOUGHNESS OF IN SITU SYNTHESISED TINP-ALNP/AL COMPOSITE

The effect of particle size, particle volume fraction, and matrix microstructure on the fracture initiation toughness of in situ TiNp-AlN/Al composite was examined. The composites were Al matrix reinforced with 7.8 to 19.6 vol pct of TiN and AlN particles produced in situ by S-V-L reaction synthetics. The average particle diameters of TiN and AlN were 3.5 and 0.9 micrometer respectively, which were distributed in Al matrix dispersedly. The room-temperature plane-strain toughness measured using three point bending specimens ranged from 12.7 to 38.5 MPa. Toughness was adversely affected by increase in TiNp-AlNp volume fraction. Fractography revealed that these composite failed in a ductile manner, with voids initiating at the in situ reinforcing TiN and AlN particles. The experimentally measured plane-strain toughness properties of in situ TiNp-AlNp/Al composite agree with the Rice and Johnson model.