Mechanical properties and microstructural evaluation of chromium containing hard coatings on Fe-Mn-Al alloy

Engineering Components with hard coatings usually exhibit improved service behavior and increased lifetime. Pack chromization and r.f. magnetron sputtering techniques are employed to deposit chromium carbides and chromium nitride on the surface of austenitic Fe-30.6Mn-6.8Al-0.9C alloy. The (Cr,Fe)(2)N1-x and Cr23C6, phases are found on the chromized surface, while the internal part of chromized layer is Cr7C3 phase. In the sputtered film, the CrN phase is observed. The chromized layer exhibits higher microhardness than that of sputtered CrN film on Fe-Mn-Al alloy measured by ultrahardness tester. The conformal cracking and partial chipping failures are found in scratch track of chromized layer, whereas conformal cracking and very few chipping failures are observed in CrN coating. The critical load L-CI and L-C2 values for chromium carbides layer are higher than that of sputtered CrN film.. Both coatings possess sufficient adhesion strength, which equals to HF1 or even better by Rockwell-C test.