Microstructural Evolution and Mechanical Properties of AZ91 and SiCp/AZ91 Magnesium Alloys upon Rapid Solidification/Powder Metallurgy Followed by Hot Extrusion

2010 ◽  
Vol 146-147 ◽  
pp. 734-737
Author(s):  
Hui Yu ◽  
Hua Shun Yu ◽  
Zhen Ya Zhang ◽  
Guang Hui Min ◽  
Cheng Chen

In this study, AZ91 and SiC particulates reinforced AZ91 (SiCp/AZ91) magnesium alloys were successfully fabricated using rapid solidification/powder metallurgy technique followed by hot extrusion. Microstructural evolution and mechanical properties of the monolithic AZ91 and SiCp/AZ91 magnesium alloys were evaluated. SiC particulates were well distributed with only few agglomerated particles. The porosity level and microhardness increased as SiCp content increased because the increased surface area of SiCp, harder ceramic phases and SiCp acted obstacles to the motion of dislocations. In addition, an increase in particulate reinforcement content was observed to decrease mechanical properties of the composite compared with the unreinforced counterpart due to increasing agglomerating regions and porosity, brittle interface debonding between matrix and SiCp.

2005 ◽  
Vol 475-479 ◽  
pp. 2789-2794 ◽  
Author(s):  
C.Y. Chen ◽  
Chi Y.A. Tsao

ray forming was employed to refine the microstructures of AZ91 and AZ91-3.34wt%Si Mg alloys during solidification by means of rapid solidification generated at atomization and droplet flight stages. The process parameters of spray forming were varied to reduce the porosity level and improve the morphology of the billet preforms. As-spray-formed microstructures were characterized using OM, SEM/EDS, and XRD, which were compared with as-cast microstructures. The significant differences of grains, Mg2Si and Mg17Al12 in morphology and in size between as-spray-fromed and as-cast materials are mainly due to fast cooling and solidification rates of spray forming process. Supersaturated matrix is found in as-spray-formed materials due to rapid solidification generated by spray forming. Overall, spray-formed materials are shown to have four characteristics, which are much finer microstructures, uniformly distributed phases, equiaxed-shaped phases, and supersaturated matrix.


2012 ◽  
Vol 186 ◽  
pp. 120-123 ◽  
Author(s):  
Tomasz Tokarski

The present paper reports an experimental investigation of rapid solidification (RS) influence on the structure and mechanical properties of commercial AZ91 magnesium alloy. In order to obtain RS material melt spinning process was applied in protective atmosphere, resulting in formation of 50 to 100 μm thickness RS ribbons. Application of plastic consolidation (PC) by hot extrusion to the highly fragmented magnesium strips allowed to obtain high bulk strength material. It was found that yield strength (YS) and ultimate tensile strength (UTS) of RS+PC material with comparison to the cast and extruded samples were increased from 220 MPa to 303 MPa and from 287 MPa to 385 MPa, respectively, while plasticity of the RS material was slightly decreased. It was noticed that the grain size of both materials was at the same level of 2 μm, thus higher mechanical properties of RS material was ascribed to dispersion strengthening caused by the high amount of fine (below 50 nm in diameter) Mg17Al12phases evenly distributed in the material structure.


1998 ◽  
Vol 553 ◽  
Author(s):  
A. Inoue ◽  
H. M. Kimura

AbstractBy the control of composition, clustered atomic configuration and stability of the supercooled liquid in the rapid solidification and powder metallurgy processes, high-strength Al-based bulk alloys containing nanoscale nonperiodic phases were produced in AI-Ln-LTM, AI-ETM-LTM and Al-(V, Cr, Mn)-LTM (Ln=lanthanide metal, LTM=VII and VIII group metals, ETM=IV to VI group metals) alloys containing high Al contents of 92 to 95 at%. The nonperiodic phases are composed of amorphous or icosahedral (I) phase. In particular, the Al-based bulk alloys consisting of nanoscale I particles surrounded by Al phase exhibit much better mechanical properties as compared with commercial Al base alloys. The success of producing the Al-based alloys with good engineering properties by use of I phase is important for future development of I-based alloys as practical materials.


2010 ◽  
Vol 667-669 ◽  
pp. 997-1002
Author(s):  
Tomasz Tokarski

Magnesium and its alloys are attractive candidates for automotive and aerospace applications due to their relatively high strength and low density. However, their low ductility determined by hcp structure of material results in limitation of plastic deformation processing. In order to improve ductility as well as mechanical properties, structure refinement processes can be used. It is well known that effective refining of the material structure can be achieved by increasing the cooling rate during casting procedures, hence rapid solidification process (RSP) has been experimented for the fabrication of magnesium alloys. The present paper reports an experimental investigation on the influence of rapid solidification on the mechanical properties of AM60 magnesium alloy. In order to obtain RS material melt spinning process was applied in protective atmosphere, resulting in formation of RS ribbons. Following consolidation of the RS material is necessary to obtain bulk material with high mechanical properties, as so hot extrusion process was applied. It was noticed that application of plastic consolidation by hot extrusion is the most effective process to achieve full densification of material. For comparison purposes, the conventionally cast and hot extruded AM60 alloy was studied as well. The purpose of the present study was to investigate in detail the effect of rapid solidification and extrusion temperature on the structure and mechanical properties of the materials.


2021 ◽  
Vol 105 ◽  
pp. 8-16
Author(s):  
Guttikonda Manohar ◽  
Krishna Murari Pandey ◽  
Saikat Ranjan Maity

Metal matrix composites attain a significant position in Industrial, defense, structural and automobile applications. To amplify that strategy there is a need to find out the conditional behavior of the composites and enhancing the properties will be mandatory. The present work mainly investigates on the effect of processing parameters like densification rates, sintering temperature, reinforcement content on the microstructure, mechanical properties of the Al7175/B4C composite material fabricated by mechanical milling and powder metallurgy techniques. Results show there is a grain size reduction and refinement in the composite material through ball milling operations and along with that increasing B4C content in the composite powders make milling conditions very effective. Increasing the sintering temperature results in a consistent grain growth along with that porosity level decreases up to a limit and then attain a steady state, the strength of the composites increases with compaction pressures but reinforcements content effects the strength of the material by losing its ductility making it brittle.


2021 ◽  
Vol 853 ◽  
pp. 156768 ◽  
Author(s):  
Shima Ehtemam-Haghighi ◽  
Hooyar Attar ◽  
Ilya V. Okulov ◽  
Matthew S. Dargusch ◽  
Damon Kent

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