Surface alloying of Ti-6Al-4V with zirconium by pulsed electron-beam melting of film – substrate system


Surface alloying of Ti-6Al-4V with zirconium by pulsed electron-beam melting of film – substrate system

Rotshtein, V. P.; Markov, A. B.; Proskurovsky, D. I.; Kagadei, V. A.; Guenzel, R.; Shevchenko, N.; Reuther, H.; Shulov, V. A.

Evolution of chemical and phase composition of the surface layers of Ti-6Al-4V subjected to surface alloying with zirconium has been studied. Alloying was carried out by liquid-phase mixing of multilayer systems of type (Ti/Zr) film on (Ti-6Al-4V alloy) substrate by a low-energy, high-current electron beam with the following parameters: pulse duration 2.5 µs, beam energy density 2.5-3 J/cm2. The number of pulses and the overall thickness of coating was ranging from 1 to 5 and from 500 to 800 nm, respectively. It has been recognized using X-ray analysis, scanning electron microscopy and electron X-ray microanalyzer, that surface layer after one-pulsed melting has a two-phase microstructure consisting of matrix solid solution of titanium with ~ 23 at.% of zirconium and a relatively pure (~ 4.5 at.% Zr) titanium particles of micron dimensions. The formation of such a microstructure takes place owing to segregation of solid solution at high-rate cooling (~ 109 K/s) of melted Ti-Zr alloy. The following vacuum annealing (550 0С, 2 hours) courses a decrease in the size of particles and a reduction in zirconium concentration in precipitations of titanium to ~ 1 at.% whereas zirconium concentration in the matrix increases and reaches 26 at.%. Auger electron spectroscopy revealed that in the latter case a thickness of surface alloy is 1-2 µm and an average concentration of zirconium equals to 20 at.%. The concentration of aluminum and vanadium is 8 and 6 times less then that of untreated Ti-6Al-4V alloy, respectively. An increase in number of pulses results in a decrease in zirconium concentration near the surface due to its evaporation. Corrosion tests in 1% NaCl solution showed that surface alloying of Ti-6Al-4V with Zr leads to approximately one order of magnitude higher corrosion resistance than that for untreated specimen.

Keywords: Ti-6Al-4V; surface alloying; zirconium; electron beam

  • Lecture (Conference)
    8th International Conference on Modification of Materials with Particle Beams and Plasma Flows, 10.-15.09.2006, Tomsk, Russia
  • Russian Physics Journal 49(2006)8, 262-267

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Publ.-Id: 9146