Thermodynamics and kinetics of in-situ formation of TiAl3/7075 composites

Hong, Yi; Ai, Fanrong; Chen, Xiaohui

doi:10.1007/s11595-013-0737-y

Cited by 1 publication

(1 citation statement)

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“…Compacts of Ti and Al particles are known to initiate a self-sustaining combustion reaction at an adiabatic temperature of 1300 C that yields the c phase as the final product; 40 this reaction proceeds by forming e phase in an exothermic reaction. The heat generated in this intermediate step further melts Al, heats the compact and activates the diffusion needed to transform e to c. 40,41 Increasing the initial temperature of the Ti-Al compact 40 and decreasing the grain size of the Ti 40,42 result in a short initiation time for this selfsustaining reaction. The decrease in the Ti grain size also enhances the speed of the self-sustaining reaction wave front.…”

Section: B Steady-state Condition Of the Converted Layers And The Efmentioning

confidence: 99%

Morphology and microstructure evolution of Ti-50 at.% Al cathodes during cathodic arc deposition of Ti-Al-N coatings

Syed

Zhu

Polcik

et al. 2017

Journal of Applied Physics

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Today's research on the cathodic arc deposition technique and coatings therefrom primarily focuses on the effects of, e.g., nitrogen partial pressure, growth temperature, and substrate bias. Detailed studies on the morphology and structure of the starting material-the cathode-during film growth and its influence on coating properties at different process conditions are rare. This work aims to study the evolution of the converted layer, its morphology, and microstructure, as a function of the cathode material grain size during deposition of Ti-Al-N coatings. The coatings were reactively grown in pure N 2 discharges from powder metallurgically manufactured Ti-50 at.% Al cathodes with grain size distribution averages close to 1800, 100, 50, and 10 lm, respectively, and characterized with respect to microstructure, composition, and mechanical properties. The results indicate that for the cathode of 1800 lm grain size the disparity in the work function among parent phases plays a dominant role in the pronounced erosion of Al, which yields the coatings rich in macro-particles and of high Al content. We further observed that a reduction in the grain size of Ti-50 at.% Al cathodes to 10 lm provides favorable conditions for self-sustaining reactions between Ti and Al phases upon arcing to form c phase. The combination of self-sustaining reaction and the arc process not only result in the formation of hole-like and sub-hole features on the converted layer but also generate coatings of high Al content and laden with macro-particles.

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