oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Microstructural Analysis of AM50/Mg2Si Cast Magnesium Composites  [PDF]
M.A. Malik,K. Majchrzak,K.N. Braszczyńska-Malik
Archives of Foundry Engineering , 2012,
Abstract: AM50/Mg2Si composites containing 5.7 wt. % and 9.9 wt. %. of Mg2Si reinforcing phase were prepared successfully by casting method.The microstructure of the cast AM50/Mg2Si magnesium matrix composites was investigated by light microscopy and X-ray diffractometry (XRD). The microstructure of these composites was characterized by the presence of α-phase (a solid solution of aluminium in magnesium), Mg17Al12 (γ-phase), Al8Mn5 and Mg2Si. It was demonstrated that the Mg2Si phase was formed mainly as primary dendrites and eutectic.
Microstructural analysis of as-cast Mg–Ag–Di magnesium alloy  [PDF]
A. ?ydek,M. Religa,K.N. Braszczyńska-Malik
Archives of Foundry Engineering , 2010,
Abstract: Microstructure of as-cast Mg – 2.4 wt.% Ag – 2.5 Di alloy have been examined by means of light microscopy, scanning microscopy (SEM+EDX) and X-ray diffraction (XRD). Results showed that the as-cast dendritic microstructure of the investigated alloy was characterized by divorced eutectic of primary α-phase and intermetallic phases Mg12Di, MgAg2Di and Mg3(Ag, Di) – type. Intermetallic phases with polygonal and needle –like morphology were located inside α-phase.
Microstructural Characterization of the As-cast AZ91 Magnesium Alloy with Rare Earth Elements  [PDF]
A. Grzybowska,K.N. Braszczyńska-Malik
Archives of Foundry Engineering , 2012,
Abstract: Microstructural analysis of as-cast Mg-9Al-0.9Zn-xRE (x = 0, 1, 2, 3, 5 wt.%) magnesium alloys is presented. Light microscopy (LM) andscanning electron microscopy (SEM+EDX) were used to characterized the obtained material. The results revealed that the as-cast AZ91alloy consists of α – Mg matrix, binary eutectic + (where is Mg17Al12). While rare earth elements were introduced to the Mg-Al-Znalloy new Al11RE3 phase was formed. Additionally, in the experimental alloys instead of Al-Mn phase, ternary Al-Mn-RE compound was observed. What is more, the influence of RE addition on the area fraction of eutectic and needle-like phase was analysed. With increasing addition of RE, the amount of γ phase decreased, but the amount of Al11RE3 phase increased.
Effect of Casting Parameters on the Microstructural and Mechanical Behavior of Magnesium AZ31-B Alloy Strips Cast on a Single Belt Casting Simulator  [PDF]
Ahmad Changizi,Mamoun Medraj,Mihaiela Isac
Advances in Materials Science and Engineering , 2014, DOI: 10.1155/2014/101872
Abstract: Strips of magnesium alloy AZ31-B were cast on a simulator of a horizontal single belt caster incorporating a moving mold system. Mixtures of CO2 and sulfur hexafluoride (SF6) gases were used as protective atmosphere during melting and casting. The castability of the AZ31-B strips was investigated for a smooth, low carbon steel substrate, and six copper substrates with various textures and roughnesses. Graphite powder was used to coat the substrates. The correlation between strip thickness and heat flux was investigated. It was found that the heat flux from the forming strip to the copper substrate was higher than that to the steel substrate, while coated substrates registered lower heat fluxes than uncoated substrates. The highest heat flux from the strip was recorded for casting on macrotextured copper substrates with 0.15?mm grooves. As the thickness of the strip decreased, the net heat flux decreased. As the heat flux increased, the grain sizes of the strips were reduced, and the SDAS decreased. The mechanical properties were improved when the heat flux increased. The black layers which formed on the strips’ surfaces were analyzed and identified as nanoscale MgO particles. Nano-Scale particles act as light traps and appeared black. 1. Introduction Magnesium is the lightest structural metal in common use [1]. Similarly, supplies of magnesium ores are virtually inexhaustible. Magnesium alloys normally have very good castability and machinability, as well as excellent specific strength and stiffness [2]. However magnesium alloys have some difficulty during rolling due to hexagonal close packed (hcp) lattice structure [3]. Meanwhile, a fine grain structure increases strength and ductility by promoting the operation of nonbasal slip systems and limiting twinning in magnesium alloys [4]. Strip casting of magnesium has become important in recent years. For reducing the cost of thin sheets of magnesium alloys, strip casting technologies such as horizontal single belt casting (HSBC), twin roll casting (TRC), and twin belt casting (TBC) have been developed [3]. With a strip casting process, magnesium alloy strips can typically be produced in thicknesses of 1–10?mm [1]. Direct strip casting, or HSBC, as a near-net-shape casting process, has potential use in the processing of aluminum, copper, zinc, and lead alloys, directly into sheet products. Generally, most metals and alloys are amenable to direct casting into plates, strips, or ribbons. However, a metallurgical understanding of these materials is needed to determine their suitability for casting into
Microstructure and Mechanical Behavior of Squeeze Cast SiCw/AZ91 Magnesium Matrix Composites

Mingyi ZHENG,Kun Wu,Congkai YAO,

材料科学技术学报 , 2001,
Abstract: The interfacial microstructure and tensile properties of the squeeze cast SiCw/AZ91 Mg composites were characterized. There exist uniform, line and discrete MgO particles at the interface between SiC whisker and magnesium in the composites using acid aluminum phosphate binder. The interfacial reaction products MgO are beneficial to interfacial bonding between SiCw and the Mg matrix. resulting in an improvement of the mechanical properties of the composite.
Raman Tensor Calculation for Magnesium Phthalocyanine  [PDF]
Jaroslav Tobik,Erio Tosatti
Physics , 2005, DOI: 10.1016/j.susc.2005.11.066
Abstract: We present ab-initio density functional (DFT) calculations of the vibrational spectra of neutral Magnesium phthalocyanine (MgPc) molecule and of its Raman scattering intensities.
Quantitative procedure for evaluation of microstructure of cast Mg-Al-Ca-Sr magnesium alloy  [PDF]
T. Rzychoń
Archives of Foundry Engineering , 2010,
Abstract: In this paper the microstructural characterization of ingot MRI-230D magnesium alloy and quantitative procedure for evaluation of microstructure are presented. The optical and scanning electron microscopy were used to study the morphology of microstructural compounds in this alloy. The X-ray diffraction was used to determination of phase composition. The as-cast microstructure of MRI-230D magnesium alloy containing aluminum, calcium and strontium consists of the dendritic α-Mg and such intermetallic compounds as: Al2Ca, Al4Sr and AlxMny. In the purpose quantitative description of microstructure semi-automatic procedures using Met-Ilo image analysis were developed. Prepared semi-automatic procedures allow a fast determination of phase content in MRI-230D alloy using light microscopy and will be useful in the quality control of MRI-230D ingots.
Synergy effect of heat and surface treatment on properties of the Mg-Al-Zn cast alloys  [PDF]
T. Tański
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: The aim of this paper is to present the results of the author’s own investigations concerning heat and surface treatment of Mg-Al-Zn magnesium alloys.Design/methodology/approach: The test results presented concern the characteristics of synergic heat and surface treatment impact on the structure and properties of Mg-Al-Zn cast magnesium alloys. The surface treatment of the magnesium alloys was carried out with the use of chemical and physical deposition methods from PA CVD and CAE PVD gas phase and laser surface treatment, including in particular laser feeding of hard ceramic particles into the surface of materials produced, enabling the production of a quasi-composite MMCs (Metal Matrix Composites) structure. The tests of the surface and internal structure of materials with the use of macro- and microscopic methods were made with the use of light, transmission and scanning electron microscopy as well Raman spectrometry and X-ray phase analysis. The physical and mechanical properties of magnesium alloys after the standard heat and surface treatment operations were tested by methods appropriate for the properties.Findings: The results of mechanical and functional properties measurements of heat treated samples confirms, that the performed heat treatment, consisting of solution heat treatment with cooling in water, as well aging with cooling in air, causes strengthening of the MCMgAl12Zn1, MCMgAl9Zn1 and MCMgAl6Zn1 cast magnesium alloys according to the precipitation strengthening mechanism, induced by inhibition of dislocation movement due to the influence of strain fields of the homogeny distributed γ-phase Mg17Al12 precipitates. The combination of properly chosen heat treatment with the possibilities of structure- and phase composition modeling of the magnesium alloys matrix using laser feeding provides an additive increase of mechanical and functional properties by significant grain refinement and production of micro-composite layers with homogeny distributed dispersion phases particle and characteristic zone structure. Increase of mechanical and functional properties of the investigated alloys is also possible by creating coatings on the surface from the gas phase.Practical implications: Achieving of new operational and functional characteristics and properties of commonly used materials, including the Mg-Al-Zn alloys is often obtained by heat treatment, ie, precipitation hardening and/or surface treatment due to application or manufacturing of machined surface layer coatings of materials in a given group of materials used for different surf
Laser surface treatment of cast magnesium alloys  [PDF]
L.A. Dobrzański,J. Domaga?a,T. Tański,,A. Klimpel
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The goal of this work was to investigate influence of laser treatment on structure and properties MCMgAl3Zn1, MCMgAl6Zn1, MCMgAl9Zn1 and MCMgAl12Zn1 cast magnesium alloys.Design/methodology/approach: Tests were made on the experimental MCMgAl3Zn1 MCMgAl6Zn1 MCMgAl9Zn1 and MCMgAl12Zn1 casting magnesium alloys. Laser treatment was made using the Rofin DL020 HPDL high power diode laser in the argon shield gas cover with the technique of the continuous powder supply to the remelted pool area.Findings: Investigations of the surface layers carried out confirm that laser treatment of the surface layer of the Mg-Al-Zn casting magnesium alloys is feasible using the HPDL high power diode laser ensuring better properties compared to alloys properties after the regular heat treatment after employing the relevant process parameters. Occurrences were found based on the metallographic examinations of the remelted zone (RZ) and the heat affected zone (HAZ) in alloyed surface layer of the investigated casting magnesium alloy.Research limitations/implications: This investigation presents different laser power and in this research was used two powders, namely tungsten-, and titanium carbide.Practical implications: Reinforcing the surface of cast magnesium alloys by adding TiC and WC particles is such a possible way to achieve the possibilities of the laser melt injection process, which is a potential technique to produce a Metal-Matrix Composite (MMC) layer in the top layer of a metal workpiece.Originality/value: The originality of this work is applying of High Power Diode Laser for alloying of magnesium alloy using hard particles like tungsten- and titanium carbide.
Investigations of microstructure and dislocations of cast magnesium alloys  [PDF]
T. Tański,L.A. Dobrzański,K. Labisz
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The microstructures and the dislocation arrangements in the cast magnesium alloy have been investigated using transmission electron microscopy and high-resolution transmission electron microscopy. In this paper are presented also the results of phase morphology investigation of an new developed Mg alloy. Such studies are of great interest for the metal industry, mainly the automobile industry, were the improvement of cast elements quality is crucial for economic and quality reason and depends mainly on properly performed controlling process of the production parameters. There are presented especially the effect of heat treatment on the size and distribution of the precipitation occurred in the matrix.Design/methodology/approach: The basic assumptions of this work are realised an Universal Metallurgical Simulator and Analyzer. The solidification process itself is analysed using the UMSA device by appliance of the Derivative Thermo Analysis. The thermal analysis was performed at a low but regulated cooling rate in a range of 0.2 oC to ca. 3 oC. Cooling curve for the thermal analysis was performed using a high sensitivity thermocouples of the K type, covered with a stainless steel sheath. The data were acquired by a high speed data acquisition system linked to a PC computer. Two different types of samples were used, bulk-cylindrical, and thin-walled cylindrical. Metallographic investigation were made on cross section samples of a engine bloc. Non-equilibrium heating and cooling process conditions were applied to achieve changes in shape and distribution of the phases such as Al2Cu and Si.Findings: During the investigation Dislocation networks are found to increase with deformation in all cases. The dislocation networks have been found in the g- Mg17Al12 phase as well as in the matrix in the investigation magnesium alloys. The crystallographic orientation relationship are: (1 01) α-Mg ║ (10 ) Mg17Al12 and [11 0] α-Mg ║ [111] Mg17Al12. Precipitation of the g-Mg17Al12 phase are mostly of the shape of roads, and the prevailing growing directions are the directions <110> α-Mg.Research limitations/implications: The investigations were performed using standard metallographic investigation as optical, scanning and transmission electron microscopy methods, also electron diffraction methods were applied for phase identification.Originality/value: The originality of this work is based on applying of regulated cooling rate of magnesium alloy for structure and mechanical properties changes. In this work the dependence between the regulated heat treatment, chem
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.