Effects of electron beam treatment on Ti(1-x)AlxN coatings on steel

Ti(1-x)AlxN hard coatings were prepared by reactive magnetron sputtering onto steel substrates. Composition and mechanical properties of the coatings could be varied using different target combinations. The prepared samples were subsequently treated by a high energy (60 key) electron beam (EB). Martensitic hardening of the steel material occurred. It was found that composition and mechanical properties of the coatings remained nearly equal compared to untreated sample surfaces. The hardening depth profiles of the samples were strongly influenced by the coating. In the coating-interface region significant changes of the composition profile, caused by the electron beam (EB) processing, were observed. The coating adhesion, evaluated using scratch tests, could be clearly improved if proper Electron beam hardening (EBH) parameters were chosen. The unequal hardening profiles observed after EBH on coated and uncoated samples can be explained by different backscattered electron yields and by different electron ranges.