We have examined fatigue crack propagation behavior in the [ferrite/bainite] Hybrid materials with different hardness under a constant stress intensity factor range. It was found that crack propagation in the ferrite phase decelerated with reaching to the [ferrite/bainite] interface, probably due to supression of plastic deformation at the crack tip. This suppression tendency of the crack propagation became higher when hardness difference between ferrite and bainite was larger. In the case with the highest hardness difference, fatigue crack did not pass through the [ferrite/bainite] interface. Lower crack propagation rate was also found in the bainite which showed higher work softening due to crack propagation.

A few studies on the synthesis of titanium aluminum nitride (Ti, Al)N films have attracted interests, in particular as an alternative to the widely used TiN films, to obtain wear-protective hard coating with higher oxidation resistance at elevated temperature. Here, the (Ti, Al)N films were prepared by depositing Ti and Al metal vapor under simultaneous irradiation of N ions, that is ion mixing and vapor deposition (IVD) technique. With an increase of evaporation Al/Ti and/or transport ratio (Ti + Al)/N, a single-phase of NaCl structure in the films transformed into that of wurtzite structure through a two-phase mixture consisting of NaCl and wurtzite structure. Based on the revelation of twophase structure, therefore, the optimum preparation conditions for wear-and corrosion-resistive hard coating were identified. The (Ti, Al)N films were also highly resistant against oxidation. Consequently, the results suggest that the Al oxide layers formed on the top of (Ti, Al)N films during elevated temperature oxidation tests protect the films from further oxidation.

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