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AgSnBi powder consolidated by composite mode of deformation

100%

Richert M. , Richert J. , Leszczyńska-Madej B. , Hotloś A. , Maślanka M. , Pachla W. , Skiba J.

2010

tom Vol. 39, nr 2

161-167

Purpose: The objective of this work present the characterization of microstructure and properties of consolidated powder AgSn7.5Bi0.5 by using composition of cyclic extrusion compression (CEC) and hydrostatic extrusion (HE) methods. As the final product the wires of 3 mm in diameter were obtained. The comparison of powder properties after CEC deformation and after the combined deformation CEC and HE is presented. Design/methodology/approach: The investigated samples contained consolidated by large plastic deformations particles of AgSnBi. The samples were deformed by the CEC method in the range of true strains = 0.32 up to .= 25.2 and then additionally were extruded to . = 1.85. The systematic observations by optical microscopy were performed for determination of the quality of particle joints. The microstructure was observed by optical, scanning and transmission electron microscopy. Microhardness was measured and areas around indentations of microhardness penetrator were observed. This allows evaluated resistance of consolidated material against local cracking under the penetrator load. Findings: Microstructure of consolidated AgSnBi powder was finding at the cross sections of samples as consisting from almost equiaxial grains, which size decreasing with the increasing of plastic deformations. The microhardness of samples strongly increase in the few first cycles (to about . = 2 of CEC) and then keeps almost the same level of about žHV = 107 - 111 to the strain of about .= 25. Inside the consolidated granules subgrains/grains with the average size of about 77 nm, after the . = 25, were found. Research limitations/implications: This paper presents results for one alloy - MC MgAl3Zn1 only, cooled with three different solidifications rate i.e. 0.6, 1.2 and 2.4°C/s, for assessment for the liquidus and solidus temperatures and its influence on the mechanical properties and structure. Practical implications: The parameters described can be applied in metal casting industry for selecting magnesium ingot preheating temperature for semi solid processing to achieve requirements properties. Originality/value: The paper contributes to better understanding and recognition an influence of different solidification condition on non-equilibrium thermal parameters of magnesium alloys.

AgSnBi consolidated by cyclic extrusion compression

100%

Richert M. , Richert J. , Hotloś A. , Leszczyńska-Madej B. , Maślanka M. , Mroczkowski M.

tom Vol. 31, nr 3

510-513

The work presents investigations of structure and microhardness of AgSnBi powder consolidated by cyclic extrusion compression (CEC) in the range of strains q = 0.46÷25.3, which corresponds to 1÷60 of deformation cycles. The essential decreasing of powder granules size was found after the deformation. Particles diminished from 40 um in initial powder to about 17 um after the q = 25.3. Inside powder particles subgrains/nanograins were found of about 100 nm in diameter average. The microhardness of powder strongly increases just after the first cycle of CEC, and then merely increases of about 8% from 101 to about 110 uHV after q = 25.3. The estimation of consolidation degree was evaluated by searching of cracks around the microhardness penetrator indentations inside the samples. No cracks or voids were found in the properly consolidated areas. At outer surfaces of samples contacting with tool walls some cracking were observed penetrating of about 100÷200 um inside samples.

Praca przedstawia badania struktury i mikrotwardości proszku AgSnBi konsolidowanego metodą CWS w zakresie odkształceń q= 0,46÷25,3, co odpowiada 1÷60 cyklom odkształcenia. Stwierdzono istotne obniżenie się wielkości granul proszku po odkształceniu. Cząstki zmniejszyły sie od 40 ?m w proszku wyjściowym do 17 um po odkształceniu q = 25,3. Wewnątrz granul wystąpiły podziarna/nanoziarna o średniej średnicy 100 nm. Mikrotwardość proszku gwałtownie wzrosła po pierwszym cyklu odkształcenia, po czym wzrosła zaledwie o 8% od 101 do 110 uHV po odkształceniu q = 25,3. Ocenę stopnia konsolidacji przeprowadzono, poszukując pęknięć wokół odcisków mikrotwardości wewnątrz próbek. Nie znaleziono żadnych pęknięć i nieciągłości w prawidłowo skonsolidowanych obszarach. Na zewnętrznej powierzchni próbek kontaktującej się ze ściankami narzędzia obserwowano pęknięcia penetrujące w głąb próbki na głębokość 100÷200 um.