Phase transformations in ultra-fine grained titanium alloys
| Thesis title in Czech: | Fázové transformace v ultra-jemnozrnných slitinách titanu |
|---|---|
| Thesis title in English: | Phase transformations in ultra-fine grained titanium alloys |
| Key words: | metastabilní slitiny titanu; metody intenzivní plastické deformace; fázové transformace; precipitáty fáze α |
| English key words: | metastable β titanium alloy; severe plastic deformation (SPD) methods; phase transformations; α phase precipitation |
| Academic year of topic announcement: | 2014/2015 |
| Thesis type: | dissertation |
| Thesis language: | angličtina |
| Department: | Department of Physics of Materials (32-KFM) |
| Supervisor: | doc. PhDr. RNDr. Josef Stráský, Ph.D. |
| Author: | hidden - assigned and confirmed by the Study Dept. |
| Date of registration: | 15.09.2015 |
| Date of assignment: | 15.09.2015 |
| Confirmed by Study dept. on: | 02.10.2015 |
| Date and time of defence: | 19.06.2019 09:00 |
| Date of electronic submission: | 30.04.2019 |
| Date of submission of printed version: | 30.04.2019 |
| Date of proceeded defence: | 19.06.2019 |
| Opponents: | doc. Ing. Ladislav Kalvoda, CSc. |
| prof. Ing. Dalibor Vojtěch, Dr. | |
| Advisors: | prof. RNDr. Miloš Janeček, CSc. |
| RNDr. Petr Harcuba, Ph.D. | |
| prof. Ing. Hanuš Seiner, Ph.D., DSc. |
| Guidelines |
| Student will undertake complex investigations of ultra-fine grained (UFG) titanium alloys prepared by severe plastic deformation (SPD) techniques. UFG microstructure evolution with imposed strain during SPD will be studied. Focusal point is to determine the effect of UFG microstructure on phase transformations in metastable beta Ti alloys. Finally, the relations between processing, achieved microstructure, phase transformations kinetics and physical properties shall be described. Achieved experimental results will be discussed on a broad theoretical basis. |
| References |
| G. Lutjering, J.C. Williams; Titanium; Springer; 2007
A.P. Zhilayev, T.G. Langdon; Using high-pressure torsion for metal processing: Fundamentals and applications; Prog Mat Sci 53; 2008 O. Srba; Komplexní studium jemnozrnných polykrystalů Cu a slitiny CuZr připravených metodami equal channel angular pressing a high pressure torsion; disertační práce; 2011 M. Janeček, J. Stráský, J Čížek, P. Harcuba, K. Václavová, V.V. Polyakova, I.P. Semenova; Mechanical properties and dislocation structure evolution in Ti6Al7Nb alloy processed by high pressure torsion, Met Mat Trans, April 2013 M. Janeček, J. Čížek, J. Stráský, K. Václavová, P. Hruška, V. Polyakova, S. Gatina, I. Semenova. Microstructure evolution in solution treated Ti15Mo alloy processed by high pressure torsion. Materials characterization. 2014, vol. 98, pp. 233-240. J. Šmilauerová, Master thesis: Phase transformations and microstructure changes in TIMET LCB alloy. Charles University in Prague. 2012. D. Kent, W. L. Xiao, G. Wang, Z. Yu, M. S. Darrgusch. Thermal stability of an ultrafine grain β-Ti alloy. Materials Science and Engineering A. 2012, vol. 556, pp. 582-587. I. Weiss, S.L. Semiatin. Thermomechanical processing of beta titanium alloys – an overview. Materials Science and Engineering A. 1998, vol. 243, pp. 46-65. G. Gottstein. Physical foundations of Materials Science. Springer-Verlag. 2004. |
| Preliminary scope of work |
| Slitiny titanu nacházejí stale širší uplatnění v letectví, chemickém průmyslu a také v medicíně. Hlavními výhodami slitin titanu jsou vysoká korozní odolnost, vysoká pevnost a nízká hustota. Titan a jeho slitiny vykazují podobně jako železo a oceli různé alotropické modifikace. Vhodným chemickým složením slitin a termomechanickým zpracováním lze zásadně ovlivnit mikrostrukturu materiálu a mechanické vlastnosti. Jednou z možností jak zvýšit pevnost polykrystalického materiálu je zmenšit velikost zrn. Ultra-jemnozrnné materiály se vyznačují velikostí zrn menší než jeden mikrometr a vykazují výrazně zvýšenou pevnost. Tyto materiály mohou být připraveny různými metodami včetně metod intenzivní plastické deformace a práškové metalurgie. Těmito metodami byly již připraveny různé kovové materiály včetně titanu a některých jeho slitin. Ultra-jemnozrnné stavy specializovaných slitin titanu a vztahy mezi ultra-jemnozrnnou mikrostrukturou a fázovými transformacem ovšem dosud nebyly studovány. |
| Preliminary scope of work in English |
| Titanium alloys find ever growing application in aircraft industry, chemical industry and in medicine. Among the advantages of titanium alloys, corrosion resistance, high strength and low density are considered the most important. Titanium and its alloys exist, similarly to steels, in different allotropic configurations. Microstructure and mechanical properties can be partly controlled by chemical composition of the alloy and appropriate heat treatment. Another possibility how to increase the strength of polycrystalic material is to refine its microstructure and achieved so-called ultra fine grained structure (UFG), which is characterized by the grain size smaller than one micrometer. These materials can be prepared by several methods, including powder metallurgy and severe plastic deformation (SPD). Many metallic materials, including Ti and some Ti alloys have already been prepared by SPD tecnhniques. On the other hande, UFG condition of specialized Ti alloys and relations between UFG structure and phase transforamtions have not been studied yet. |