http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ultrasonic Treatment of Ti-5Al-0.5 V Alloy Subjected to Equal-Channel Angular Pressing
Aygul A. Mukhametgalina,Mariya A. Murzinova,Ayrat A. Nazarov,Asiya A. Samigullina,Miloš Janeček,Josef Stráský,Kristína Bartha,Jakub Čížek 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5
Microstructure and room temperature mechanical properties of α-titanium alloy Ti-5Al-0.5 V subjected to equal channelangular pressing (ECAP) and subsequent ultrasonic treatment (UST) have been studied. The ECAP was carried out at 600 °Cby route Bcand the UST at the frequency of 20 kHz and amplitude of compression-tension stresses of 100 MPa for processingtime of 60 s. The dislocation densities after ECAP and subsequent UST were estimated by x-ray diffraction and positronlifetime spectroscopy. By the latter, vacancy concentration also was determined. It has been shown that UST results in avery little increase in the dislocation density and vacancy concentration and has no considerable effect on the mechanicalproperties of the ECAP-ed titanium alloys. Basing on the data obtained and earlier published results of computer simulationsof the behavior of nonequilibrium grain boundaries in Ni and Ti under the action of ultrasound it is concluded thatthe structural transformations in Ti under UST occur at much higher stresses than in Ni, in which UST results in significantmodifications of the structure and properties.
Microstructure and corrosion properties of ultrafine-grained interstitial free steel
Hadzima, Branislav,Janeč,ek, Miloš,Estrin, Yuri,Kim, Hyoung Seop Elsevier 2007 Materials science & engineering. properties, micro Vol.462 No.1
<P><B>Abstract</B></P><P>The microstructure and the corrosion behaviour of ultrafine-grained interstitial free (IF) ferritic steel processed by equal channel angular pressing (ECAP) at room temperature following route C were investigated. Already after the first pass of ECAP, the microstructure was refined by a factor of approximately 200. On further passes, ECAP was found to lead to continuous grain refinement, while elongated grain structure produced in the first pass was retained throughout all processing cycles. After 8 passes, the microstructure comprised bands of elongated grains of average length of 500–1000nm and average width of 200–300nm. Corrosion characteristics of a non-deformed coarse grained specimen and an ultrafine-grained specimen that had undergone 8 passes of ECAP were investigated using electrochemical potentiodynamic tests. ECAP induced grain refinement does not appear to influence the electrochemical characteristics in neutral NaCl solutions. This encouraging finding demonstrates that ECAP, while enhancing mechanical characteristics, does not compromise corrosion resistance of IF steel. A protective oxidic layer is formed in alkaline NaCl solution, which reduces the corrosion rate significantly.</P>
Evolution of microstructure and hardness in AZ31 alloy processed by high pressure torsion
Strá,ská,, Jitka,Janeč,ek, Miloš,Gubicza, Jenő,Krajň,á,k, Tomá,š,Yoon, Eun Yoo,Kim, Hyoung Seop Elsevier 2015 Materials science & engineering. properties, micro Vol.625 No.-
<P><B>Abstract</B></P> <P>A commercial MgAlZn alloy (AZ31) was processed by high pressure torsion (HPT) at room temperature, resulting in an extreme microstructure refinement down to the grain size of 150–250nm. The microstructure evolution during HPT was investigated by transmission electron microscopy and X-ray diffraction line profile analysis. The microhardness was measured as a function of the distance from the center of the disk and the number of HPT revolutions. The detailed analysis of dislocation contrast factors in X-ray diffraction line profiles enables to determine the population of the different slip systems as a function of the imposed strain. The influence of microstructure and defect structure evolution on microhardness is discussed in detail.</P>