Repeated nanoscratch and double nanoscratch tests of Lu2O3 transparent ceramics: Material removal and deformation mechanism, and theoretical model of penetration depth

The single nanoscratch, repeated nanoscratch and double nanoscratch tests of Lu2O3 transparent ceramics are carried out on a nanoindenter. Theoretical models of the penetration depth in single scratch, repeated nanoscratch and double nanoscratch tests are established by taking the elastic recovery into account. The surface morphology, friction characteristics of repeated nanoscratch and elastic recovery of double nanoscratch are researched. Ductile surface with hardly cracks and burrs, and obvious pile-up at the leading edge and both sides of the scratch path are obtained. TEM results indicate that the ductile deformation mechanism of Lu2O3 transparent ceramics is a combination of poly-crystalline nano-crystallites in the inner grain and amorphous transformation. Many defects including dislocations, stacking faults, nano twins, torsion of atomic plane, fracture of atomic plane and wrong arrangement of atomic plane are induced in nano grains generated during the ductile removal process. The dominant way of subsurface crack propagation is intergranular fracture.