Enhancement of Heat Resistance of Ti6Al4V Titanium Alloy by Formation of Oxide Composite Layers Using Ultrasonic Impact Treatment
V. V. Mohylko$^{1}$, A. P. Burmak$^{1}$, M. M. Voron$^{2}$, I. A. Vladymyrskyi$^{1}$, S. I. Sidorenko$^{1}$, S. M. Voloshko$^{1}$, B. M. Mordyuk$^{3}$
$^{1}$National Technical University of Ukraine ‘Igor Sikorsky Kyiv Polytechnic Institute’, 37 Peremohy Ave., UA-03056 Kyiv, Ukraine
$^{2}$Physico-Technological Institute of Metals and Alloys, NAS of Ukraine, 34/1 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
$^{3}$G. V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
Received: 17.06.2018. Download: PDF
A modification of the surface layer of a Ti6Al4V titanium alloy is carried out using ultrasonic impact treatment (UIT) with addition of the Al$_2$O$_3$ and Cr$_2$O$_3$ powders to the deformation zone. As shown by means of x-ray diffraction phase analysis, optical and scanning electron microscopies, the surface layers of composite are formed during the UIT induced severe plastic deformation. The microhardness of the composite layers is 2 times higher than that of the matrix alloy. The high-temperature oxidation of composite layers containing Cr$_2$O$_3$ particles and the Cr$_2$O$_3$ + Al$_2$O$_3$ mixture leads to strengthening the underlying layers due to the formation of a solid solution of oxygen in the $\alpha$-phase, which is not observed in the case of a layer/coating formed with addition of Al$_2$O$_3$. According to the gravimetric analysis of samples during the cyclic high-temperature oxidation in air (20 cycles for 5 hours at a temperature of 550°C), it is concluded that the composite layer/coating saturated with Al$_2$O$_3$ particles have the highest heat resistance. This is due to the close values of the thermal expansion coefficients of Al$_2$O$_3$ coating and Ti6Al4V alloy, as opposed to the behaviour of the rough alloy and other composite layers, which are destroyed during the cyclic heating–cooling process.
Key words: ultrasonic impact treatment (UIT), composite layers, oxide powders, coating, microhardness, heat resistance.
URL: http://mfint.imp.kiev.ua/en/abstract/v40/i11/1521.html
DOI: https://doi.org/10.15407/mfint.40.11.1521
PACS: 61.43.Gt, 61.72.Ff, 62.20.Qp, 65.40.De, 68.60.Dv, 81.05.Mh, 81.65.Mq
Citation: V. V. Mohylko, A. P. Burmak, M. M. Voron, I. A. Vladymyrskyi, S. I. Sidorenko, S. M. Voloshko, and B. M. Mordyuk, Enhancement of Heat Resistance of Ti6Al4V Titanium Alloy by Formation of Oxide Composite Layers Using Ultrasonic Impact Treatment, Metallofiz. Noveishie Tekhnol., 40, No. 11: 1521—1537 (2018) (in Ukrainian)