Improving thermal stability of hard coating films via a concept of multicomponent alloying
H. Lind, R. Forsén, B. Alling, N. Ghafoor, F. Tasnádi, M.P. Johansson
We propose a design route for the next generation of nitride alloys via a concept of multicomponent alloying based on self-organization on the nanoscale via a formation of metastable intermediate products during the spinodal decomposition. We predict theoretically and demonstrate experimentally that quasi-ternary (TiCrAl)N alloys decompose spinodally into (TiCr)N and (CrAl)N-rich nanometer sized regions. The spinodal decomposition results in age hardening, while the presence of Cr within the AlN phase delays the formation of a detrimental wurtzite phase leading to a substantial improvement of thermal stability compared to the quasi-binary (TiAl)N or (CrAl)N alloys.
The local tendencies for spinodal decomposition in c-(TiCrAl)N at 1300 K. The arrows represent the most favorable directions of spinodal decomposition. The lengths of the arrows are proportional to the magnitudes of the second derivative of the free energy in that direction, indicating the strength of the decomposition trends.
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Last updated: 09/16/11