Improvement of strength and ductility of an EZ magnesium alloy by applying two different ECAP concepts to processable initial states

Publication date: Available online 20 September 2018Source: Materials Science and Engineering: AAuthor(s): Krzysztof Bryła, Maciej Krystian, Jelena Horky, Bernhard Mingler, Krzysztof Mroczka, Paweł Kurtyka, Lidia Lityńska-DobrzyńskaAbstractThe commercial magnesium alloy EZ33A was processed by Equal Channel Angular Pressing (ECAP). Two different tools were used: a conventional one with two channels and one intersection (90°), and a so-called double ECAP (D-ECAP) tool with two intersections (90° and 120°). Four passes were conducted at temperatures subsequently lowered from 350°C down to 240°C using route Bc.The as-cast, pre-deformed material and both ECAP conditions were investigated. The microstructure was revealed by means of optical microscopy, scanning and transmission electron microscopy (SEM, TEM), and X-ray diffraction. Mechanical properties were studied by Vickers hardness measurements as well as by compressive and tensile tests.The microstructure investigations show a significant grain refinement as well as fragmentation and redistribution of the hard intermetallic (Mg,Zn)12RE phase by ECAP. This effect is even more pronounced in the material processed by D-ECAP where this phase is two times finer compared to the size after conventional ECAP. Additionally, small Zn-Zr particles of a few nanometers size within grains or subgrains were observed.Microstructure changes evoked by the ECAP processing significantly affect the mechanical properties. This is especiall...
Source: Materials Science and Engineering: A - Category: Materials Science Source Type: research