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Item Microstructure Evolution in Cast Al-Zn-Mg Alloys Processed by Equal Channel Angular Pressing(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.In the present work, microstructure development and enhancement in the microhardness of Al-Zn-Mg alloys (with 5, 10, and 15% zinc) during equal channel angular pressing (ECAP) were investigated. Dendritic morphology was observed in the cast condition of all three alloys, and precipitates were situated along the inter-dendritic regions. After homogenization, precipitates in the inter-dendritic regions were uniformly distributed in the aluminum matrix and grain boundaries were developed. After 4 passes in route BC, large reduction in the grain size was observed. X-ray diffractometry showed that MgZn2 precipitate was developed in the ECAP-processed samples. Increase in the intensity of MgZn2 peaks was observed when the quantity of zinc is increased in the material. Also, changes in the intensity of XRD peaks were observed in ECAP-processed samples due to shear deformation. After ECAP, substantial increase in the microhardness was perceived. After four passes, microhardness increased to 109, 67, and 58% from the initial condition in A1, A2, and A3 alloys, respectively. Also, improvement in the microhardness was also observed when the quantity of zinc is increased in the material. © 2017, Springer Science+Business Media, LLC, part of Springer Nature and ASM International.Item Microstructure and Mechanical Properties of Cast Al-5Zn-2Mg Alloy Subjected to Equal-Channel Angular Pressing(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Manjunath, G.K.; Preetham Kumar, G.V.P.; Udaya Bhat, K.; Huilgol, P.In the present work, cast Al-5Zn-2Mg alloy was processed through equal-channel angular pressing (ECAP) in route BC up to four number of passes. Microstructure and mechanical properties were investigated on processed and unprocessed materials. In cast condition, the material was composed of dendritic structure. After homogenization treatment, large-sized grains were observed. After ECAP processing, significant grain refinement was observed. After ECAP processing, high-density dislocations and high degree of misorientation between the grains were observed. In cast material, rod-shaped precipitates were observed, while, after ECAP processing, spherical-shaped precipitates were observed. ECAP processing leads to a noticeable improvement in the mechanical properties of the material. After four passes, 122% improvement in the microhardness and 135% improvement in the ultimate tensile strength of the material were observed. After three passes, a slight decrease in the mechanical properties was observed. This is attributed to the dissolution of the metastable ?? phase, annihilation of dislocations, dynamic recrystallization and texturing during ECAP processing. Brittle fracture mode was observed in tensile testing cast and homogenized samples. After ECAP processing, fracture mode was changed into shear fracture mode. © 2018, ASM International.Item Precipitate evolution during severe plastic deformation of cast Al-Zn-Mg alloys and their thermal stability(Institute of Physics Publishing helen.craven@iop.org, 2019) Manjunath, G.K.; Huilgol, P.; Preetham Kumar, G.V.P.; Bhat, K.U.In the current investigation, an effort was made to understand the precipitate evolution process during equal channel angular pressing (ECAP) of an alloy composed of only aluminium, zinc and magnesium. For this purpose, three different compositions of cast Al-Zn-Mg alloys were selected and ECAP processed in route BC upto four passes. Microstructural observations indicated that, ECAP processing leads to refined structure possessing high density dislocations and large amount of grains with high angle grain boundaries. The precipitate volume in the alloys increased with increase in the zinc quantity in the alloy. Microstructural characterization through transmission electron microscope (TEM) and differential scanning calorimeter (DSC) revealed that, processing by ECAP results in structure having stable ? phase precipitates without the presence of GP zones and intermediate ?? phase precipitates. Thereby demonstrates that, ECAP process accelerates the precipitation kinetics and also shifts the morphology of the precipitates. Higher mechanical properties were noticed in the alloy containing large quantity of MgZn2 precipitates. © 2018 IOP Publishing Ltd.Item Effect of zinc content on the microstructure and mechanical properties of Al-Zn-Mg alloy(Elsevier Ltd, 2022) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.In the present work, Aluminium-Zinc-Magnesium alloys (5 wt%, 10 wt% and 15 wt% Zinc and 2 wt% Magnesium) were prepared by casting process in a metal die. After casting process, heat treatment was conducted to the prepared alloys. To study the consequence of Zinc on the prepared alloys microstructure and mechanical properties were investigated. In as-cast state, in all three compositions, dendrite formation was noticed. While, after homogenization heat treatment, grain boundaries were noticed. Rise in the Zinc in the material leads to enhance the secondary particles. Microhardness and tension experiments were conducted to investigate the mechanical properties. Rise in the Zinc in the material leads to enhance the microhardness and tension strength. But ductility of the material declined with rise in the Zinc in the material. © 2021