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Microstructure and mechanical properties study of the finegrained magnesium alloys processed by severe plastic deformation
Šašek, Stanislav ; Stráská, Jitka (advisor)
Two magnesium alloys (Mg-4Y-4Gd-2Ca and Mg-2Y-2Gd-1Ca) with high ignition tem- perature were successfully processed by extrusion. Mg-2Y-2Gd-1Ca alloy was addition- ally processed by equal channel angular pressing (ECAP) to achieve ultrafine-grained microstructure. The effect of extrusion parameters on fraction of recrystallized grains, grain size, and texture was revealed by EBSD analysis. The presence of Mg2Ca, REH2 and Mg5RE secondary phases was proven by SEM and TEM. Microstructural condition including distribution and morphology of secondary phase par- ticles directly affected the mechanical properties. Yield tensile stress exceeding 200 MPa was achieved in each condition. Large non-recrystallized grains with strong {10̄10} tex- ture resulted in a significant anisotropy in mechanical properties. Processing by ECAP led to a homogeneous microstructure with a mean grain size below 1 µm. ECAP condition showed superior mechanical properties with a low anisotropy. The developed and analysed microstructural condition resulted in favourable mechanical properties. The studied alloys are therefore promising for the application in aerospace industry. 1
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Mechanical properties and microstructure of ultrafine-grained magnesium alloys containg neodymium and zinc
Šašek, Stanislav ; Stráská, Jitka (advisor) ; Krajňák, Tomáš (referee)
Two experimental magnesium alloys containing neodymium and zinc (Mg- 5Nd-1Zn and Mg-1Nd-1Zn) were processed by severe plastic deformation (SPD) method - equal channel angular pressing (ECAP). The influence of the processing on the microstructure was studied by light optical microscopy (LOM), transmis- sion electron microscopy (TEM) and also scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD). A significant grain refinement was observed after the final stage of ECAP in both alloys resulting in homogenous ultra-fine grained condition. Microstructure development had a significant influ- ence on mechanical properties which were investigated by microhardness measu- rements and compression deformation tests. Both the yield compression strength σ0,2 and the microhadness significantly increased compared to the extruded/as- cast counterparts. 1
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Microstructure and mechanical properties study of the finegrained magnesium alloys processed by severe plastic deformation
Šašek, Stanislav ; Stráská, Jitka (advisor) ; Hadzima, Branislav (referee)
Two magnesium alloys (Mg-4Y-4Gd-2Ca and Mg-2Y-2Gd-1Ca) with high ignition tem- perature were successfully processed by extrusion. Mg-2Y-2Gd-1Ca alloy was addition- ally processed by equal channel angular pressing (ECAP) to achieve ultrafine-grained microstructure. The effect of extrusion parameters on fraction of recrystallized grains, grain size, and texture was revealed by EBSD analysis. The presence of Mg2Ca, REH2 and Mg5RE secondary phases was proven by SEM and TEM. Microstructural condition including distribution and morphology of secondary phase par- ticles directly affected the mechanical properties. Yield tensile stress exceeding 200 MPa was achieved in each condition. Large non-recrystallized grains with strong {10̄10} tex- ture resulted in a significant anisotropy in mechanical properties. Processing by ECAP led to a homogeneous microstructure with a mean grain size below 1 µm. ECAP condition showed superior mechanical properties with a low anisotropy. The developed and analysed microstructural condition resulted in favourable mechanical properties. The studied alloys are therefore promising for the application in aerospace industry. 1
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Effect of sintering temperature on microstructure and mechanical properties of AE42 magnesium alloy prepared by spark plasma sintering
Minárik, P. ; Lukáč, František ; Cinert, Jakub ; Šašek, S. ; Král, R.
Magnesium alloy AE42 was prepared by powder metallurgy technique of spark plasma sintering. The effect of sintering parameters, particularly sintering temperature, on the microstructure and mechanical strength was investigated. The gas-atomized powder was sintered at four temperatures in the temperature range of 400-550 °C. It was found that mechanical strength of the sintered samples was significantly affected by several microstructural features. Application of relatively high load during sintering caused deformation of the individual particles and consequent recrystallization depending on the processing temperature resulted in the release of internal strain and in grain growth. As a result, the evolution of the mechanical strength as a function of the sintering temperature was significantly affected by residual stress, grain size and coarsening of secondary phase particles.
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Mechanical properties and microstructure of ultrafine-grained magnesium alloys containg neodymium and zinc
Šašek, Stanislav ; Stráská, Jitka (advisor) ; Krajňák, Tomáš (referee)
Two experimental magnesium alloys containing neodymium and zinc (Mg- 5Nd-1Zn and Mg-1Nd-1Zn) were processed by severe plastic deformation (SPD) method - equal channel angular pressing (ECAP). The influence of the processing on the microstructure was studied by light optical microscopy (LOM), transmis- sion electron microscopy (TEM) and also scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD). A significant grain refinement was observed after the final stage of ECAP in both alloys resulting in homogenous ultra-fine grained condition. Microstructure development had a significant influ- ence on mechanical properties which were investigated by microhardness measu- rements and compression deformation tests. Both the yield compression strength σ0,2 and the microhadness significantly increased compared to the extruded/as- cast counterparts. 1
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