ISSN:
1662-8985
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The recrystallization behaviors of cold rolled aluminum alloys in electric field up to400kV/mm and the phase transformation processes of proeutectoid steels under magnetic field up to14 Tesla have been experimentally examined. It has been found that both the electric field and themagnetic field have influence on the evolution of texture and microstructure characteristics. Duringthe recrystallization annealing under the electric field of the cold-rolled 3104 aluminum alloy sheets,the electric field postpones the recovery and recrystallization progress. First principle calculation wasperformed to study the electric structures of aluminum atoms and vacancies. It shows that vacanciesthat are helpful for recovery are electrically negative. As the sample worked as anode during electricfield annealing, it was covered with positive surface charges that attract the electronegative vacanciesin the vicinity of the free surface and annihilate them. In this way, the recovery and then therecrystallization are postponed.The magnetic field applied changes the precipitation sequence of transitional carbides during lowtemperature tempering that makes the relatively high-temperature monoclinic χ-Fe5C2 carbideprecipitated without following the usual precipitation sequence, i.e. by skipping the precipitation ofthe usual orthorhombic η-Fe2C carbide. To reveal the working mechanism of this phenomenon, firstprinciple calculations were performed to study the formation energies of the two iron-carbide systemsand their electronic and magnetic structures and properties. Calculation results show that η-Fe2C haslower formation energy, which is proved by the formation sequence observed during the usual lowtemperature tempering process. However, χ-Fe5C2 has the higher magnetic moment, which enhancesthe stability under the magnetic field through magnetization. Therefore, under the magnetic field itsprecipitation tendency is increased
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.29-30.123.pdf
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