AZ80 magnesium alloy was used as experiment
materials. It contains 8.5%Al, 0.5%Zn, 0.12%Mn,
0.003%Fe, 0.02%Cu, 0.001%Ni (mass fraction) and Mg
as balance. New SIMA method was employed to
fabricate the semisolid billet of AZ80 magnesium alloy.
Firstly, as-cast AZ80 magnesium alloys with diameter of
57 mm and height of 120 mm were processed for 4
passes at 300 °C under route Bc by an equal channel die
[22]. The route Bc refers to the rotations of 90º in the
same sense between consecutive passes in the cylindrical
specimens. Sixteen AZ80 alloy billets were extruded by
EACE. Four tensile specimens were cut from each
ECAE-processed billet along the direction of extrusion.
Eight ECAE-processed billets were used as tensile and
microstructural specimens. At the same time, room
temperature tensile test and microstructural observation
were done in the eight as-cast ingots. The mechanical
properties of the tensile specimen were measured at
room temperature by a universal testing machine
(INSTRON 5569) at a crosshead speed of 0.5 mm/min.
Microstructural samples were fabricated by the standard
metallurgical technique, followed by etching in a
solution of 4.2 g picronitric acid, 10 mL ethanediol, 70
mL ethanol and 10 mL distilled water. The
microstructure was observed by using an Olympus G50
optical microscope. The other eight billets were used as
semisolid isothermal treatment (SSIT). These eight
ECAE-processed billets were isothermally treated for 10
min at various semisolid temperatures in an electrical
furnace. The various semisolid temperatures involved
530, 540, 550 and 560 °C. The AZ80 magnesium alloy
was prevented from oxidation or burning by argon gas.
The average particle size and shape factor of the solid
phases were measured using a digital image analysis
system. Average particle size and shape factor (SF) of
solid particles are calculated in each case [23].
AZ80 magnesium alloy was used as experimentmaterials. It contains 8.5%Al, 0.5%Zn, 0.12%Mn,0.003%Fe, 0.02%Cu, 0.001%Ni (mass fraction) and Mgas balance. New SIMA method was employed tofabricate the semisolid billet of AZ80 magnesium alloy.Firstly, as-cast AZ80 magnesium alloys with diameter of57 mm and height of 120 mm were processed for 4passes at 300 °C under route Bc by an equal channel die[22]. The route Bc refers to the rotations of 90º in thesame sense between consecutive passes in the cylindricalspecimens. Sixteen AZ80 alloy billets were extruded byEACE. Four tensile specimens were cut from eachECAE-processed billet along the direction of extrusion.Eight ECAE-processed billets were used as tensile andmicrostructural specimens. At the same time, roomtemperature tensile test and microstructural observationwere done in the eight as-cast ingots. The mechanicalproperties of the tensile specimen were measured atroom temperature by a universal testing machine(INSTRON 5569) at a crosshead speed of 0.5 mm/min.Microstructural samples were fabricated by the standardmetallurgical technique, followed by etching in asolution of 4.2 g picronitric acid, 10 mL ethanediol, 70mL ethanol and 10 mL distilled water. Themicrostructure was observed by using an Olympus G50optical microscope. The other eight billets were used assemisolid isothermal treatment (SSIT). These eightECAE-processed billets were isothermally treated for 10min at various semisolid temperatures in an electricalfurnace. The various semisolid temperatures involved530, 540, 550 and 560 °C. The AZ80 magnesium alloywas prevented from oxidation or burning by argon gas.The average particle size and shape factor of the solidphases were measured using a digital image analysissystem. Average particle size and shape factor (SF) ofsolid particles are calculated in each case [23].
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