Enhancement of Heat Resistance of Ti6Al4V Titanium Alloy by Formation of Oxide Composite Layers Using Ultrasonic Impact Treatment
V. V. Mohylko1, A. P. Burmak1, M. M. Voron2, I. A. Vladymyrskyi1, S. I. Sidorenko1, S. M. Voloshko1, B. M. Mordyuk3
1National Technical University of Ukraine ‘Igor Sikorsky Kyiv Polytechnic Institute’, 37 Peremohy Ave., UA-03056 Kyiv, Ukraine
2Physico-Technological Institute of Metals and Alloys, NAS of Ukraine, 34/1 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
3G. 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 Al2O3 and Cr2O3 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 Cr2O3 particles and the Cr2O3 + Al2O3 mixture leads to strengthening the underlying layers due to the formation of a solid solution of oxygen in the α-phase, which is not observed in the case of a layer/coating formed with addition of Al2O3. 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 Al2O3 particles have the highest heat resistance. This is due to the close values of the thermal expansion coefficients of Al2O3 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)