MACHINING-INDUCED SURFACE RESIDUAL-STRESS BEHAVIOR IN AL2O3-SIC NANOCOMPOSITES

The machining and subsequent annealing behavior of an Al2O3-SiC nanoco mposite (Al2O3 + 5 vol% 0.2 mu m SiC particles) was compared to that o f single-phase Al2O3. The machining-induced residual line force was de termined by measuring the extent of elastic bending in thin disk speci mens, and the surface roughness was evaluated by profilometry, The res ults showed that, when the two materials were subjected to the same gr inding conditions, they developed compressive residual stresses and su rface roughness values of similar magnitude. The maximum thickness of the residual stress layers was estimated to be similar to 10 mu m for the Al2O3 and similar to 12 mu m for the nanocomposite, A direct linea r correlation was observed between the residual force and the surface roughness for different machining treatments, Annealing of the machine d samples produced complete relaxation of residual stresses in the sin gle-phase Al2O3, whereas only partial stress relaxation occurred for t he nanocomposite.