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Methods of the modification of the surface layer by interstitial elements (oxygen, nitrogen) to improve the properties of titanium alloys


Authors: O.V Tkachuk, Ph.D., V.S. Trush, Ph.D., R.V. Proskurnyak

Presented by G.V. Karpenko Physico-Mechanical Institute of National Academy of Sciences of Ukraine.

The cycle of scientific publications consists of 27 scientific papers published during 2008-2013.

In this work, a new solution of the important scientific and technical problem –increasing of the functional properties of titanium alloys by modification of the surface layer by interstitial elements (oxygen, nitrogen) at the thermodiffusion saturation from controlled gas medium was obtained.

The effect of the nonstoichiometry of titanium nitride on the degree of its modification by oxygen as well as parameters of oxygen-containing medium on the phase composition and characteristics of the surface layers of titanium alloys after oxynitriding was determined. The tribotechnical behaviour of titanium alloys after oxynitriding was studied. The peculiarities of the corrosion behaviour of nitride and oxynitride layers in aggressive media and physiological solutions were revealed.

The effect of the increase of the durability of titanium alloys at cyclic and static loads during the formation of the modified surface layer of defined parameters by oxygen was determinedfor the first time. The physical nature of the phenomenon of the increase of the fatigue properties of titanium at the modification of the surface layer by oxygen was revealed.

The method of the modificationof the surface layer of titanium alloys by oxygen which improves their fatigue strength on 15...30 % and long-term strength and 10...15 % was developed. The methods of oxynitriding to improve the wear- and corrosion resistance of titanium alloys were developed. As compared to well-known methods of one-component saturation (nitriding), they provide the three order of magnitude decrease of the wear intensity of the pair “oxynitrided titanium –steel” and the decrease of the corrosion rate on one order in 40 % aqueous solution of sulphuric acid.

It was developed and put into production at the aircraft company “ANTONOV”the technology “Vacuum heat treatment of welded details from single-phase titanium alloys VT1-0 and PT-7M”and corresponding technological instruction. The proposed technology improves the durability of thin-walled products from titanium alloys on 20...30 %.

The results of investigations are described in 41 scientific publications, including 27 articles (9 in foreign journals), 10 abstracts and 4 patents of Ukraine. In journals, which are in the Scopus database, 12 articles have been published. The works of the authors were cited in 26 journals, general h-index is 5.