Mechanical Properties Refinement of Magnesium Alloy AZ91 via Cyclic Compression-Expansion Extrusion (CCEE) Method

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Mashoufi, Kiarash | 2021

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 54275 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Assempour, Ahmad
Abstract:
Cyclic Contraction Expansion Extrusion (CCEE) is a new Severe Plastic Deformation (SPD) method used to refine the microstructure and improve mechanical properties of Magnesium AZ91 alloy. In this study, different CCEE process zones are investigated via optical microscopy to understand this process better. The average grain size in the contraction zone decreased to 8.5 microns from an initial value of 106 microns. In the expansion zone, the average grain size was equal to 4.8 microns. Microhardness tests were conducted to study the improvements in mechanical properties. Microhardness of the sample increased from the initial value of 66 HV to 74.4 HV in the contraction zone and 88 HV in expansion zone. For more detailed investigation FE-SEM was used to observe grain boundaries
Keywords:
Microstructure ; Magnesium ; AZ91 Magnesium Alloy ; Severe Plastic Deformation ; Mechanical Properties Improvement

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