Magnesium alloys containing yttrium, gadolinium and calcium processed by Equal Channel Angular Pressing (ECAP)
Abstract
Magnesium alloys with low density and high specific strength are suitable candidates for the use in weight-saving industries, such as the aerospace industry. The use of magnesium alloys in the aerospace industry is limited because of their low flammability resistance.
Flammability resistance of magnesium alloys can be affected by alloying elements. It has been proven that rare earth metals and calcium increase resistance to ignition.
Magnesium alloy containing yttrium, gadolinium and calcium (Mg-2Y-2Gd-1Ca, wt. %) was designed for use in the aerospace industry. In order to obtain a fine-grained microstructure, alloy was processed by extrusion and also eight passes of Equal Channel Angular Pressing (ECAP).
The microstructure after extrusion was bimodal. The grain size and the degree of recrystallization depended on the parameters of extrusion.
ECAP processing led to homogenous microstructure with mean grain size less than 1 μm, which meets the parameters of ultrafine-grained alloys. The mechanical properties corresponded to the observed microstructure.
The alloy is also characterized by a high ignition temperature and is therefore promising for use in the aerospace industry. The microstructure was observed using transmission and scanning electron microscopy, including electron backscatter diffraction (EBSD).
Mechanical properties were studied using tensile/compressive deformation tests and microhardness measurements.