Structural, Mechanical, and Thermal Properties of the TiAlTaN/TiAlBN Multilayer

Abstract

A multilayer structure and incorporation of the fourth element are promising strategies to improve the properties of TiAlN coatings. In this study, the structural, mechanical, and thermal properties of the Ti0.34Al0.48Ta0.18N/Ti0.42Al0.54B0.04N multilayer, as well as the Ti0.34Al0.48Ta0.18N and Ti0.42Al0.54B0.04N monolithic coatings, were carefully researched. Coherent growth of the multilayer structure induces a single-phase cubic structure of the Ti0.34Al0.48Ta0.18N/Ti0.42Al0.54B0.04N multilayer, even though the Ti0.34Al0.48Ta0.18N and Ti0.42Al0.54B0.04N coatings have a single-phase cubic structure and a mixed cubic and wurtzite structure, respectively. The Ti0.34Al0.48Ta0.18N/Ti0.42Al0.54B0.04N multilayer reveals a higher hardness of 38.2 ± 0.9 GPa due to interfacial strengthening, corresponding to 32.4 ± 0.6 GPa of Ti0.34Al0.48Ta0.18N and 32.7 ± 0.9 GPa of Ti0.42Al0.54B0.04N. During annealing, our three kinds of coating demonstrate an age-hardening effect. The Ti0.34Al0.48Ta0.18N/Ti0.42Al0.54B0.04N multilayer presents a hardness peak of 40.0 ± 0.9 GPa at 1000 °C, whereas the Ti0.34Al0.48Ta0.18N and Ti0.34Al0.48Ta0.18N coatings show the hardness peaks of 37.1 ± 0.7 and 35.0 ± 0.6 GPa at 900 °C, respectively. Furthermore, the improved oxidation resistance is obtained by the Ti0.34Al0.48Ta0.18N/Ti0.42Al0.54B0.04N multilayer.