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RISS 인기검색어
- 검색키워드
- 저자 : M. Reihanian (검색결과 4 건)
- 무료
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- 유료
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Microstructure and Impression Creep Behavior of Al–7Si–0.3Mg Alloy with Zr Addition
M. Reihanian,Khalil Ranjbar,S. Rashno 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8
The effect of 0.25 wt% and 0.5 wt% Zr addition on the impression creep behavior of the cast A356 alloy was investigated. Optical and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS) were used forexamination of the microstructure. The impression creep test was conducted at the temperature range of 493–553 K underthe stress range of 480–680 MPa (corresponding to the normalized stresses between 0.022 and 0.03). Microstructuralinvestigations showed that the Zr addition refined the α-Al grains and modified the eutectic structure. The Zr-containingalloys were characterized by Zr-rich intermetallics, suggesting the creep resistance of the A356 alloy was improved by Zraddition. The creep resistance of the A356–0.25Zr alloy was higher than that of the A356–0.5Zr alloy that was attributed tothe morphology and the distribution of intermetallics that are rich in Zr. Results showed that the lattice self-diffusion climbcontrolledcreep was the dominant creep mechanism in all alloys.
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Effect of Rare Earth Er on Microstructure and Creep Behavior of Al–7Si–0.3Mg Alloy
S. Rashno,M. Reihanian,Khalil Ranjbar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
The effect of 0.25 wt% and 0.5 wt% rare earth Er addition on the microstructure and creep behavior of the cast A356 alloywas investigated. The microstructure of the alloys before and after the creep was evaluated by optical and scanning electronmicroscopy equipped with energy dispersive spectrometry. The creep behavior was examined by the impression creep testat the temperature range of 493 to 553 K under the stresses between 480 and 680 MPa. Results showed that the additionof Er addition caused the α-Al dendrites to refine and the morphology of the eutectic silicon to modify significantly. Themicrostructure of the A356 alloy with Er addition was characterized by Er-rich intermetallics. The lattice self-diffusionclimb-controlled creep was found to be the dominant creep mechanism in all alloys. The addition of Er improved the creepresistance of the A356 alloy and the alloy modified with 0.5 wt% Er exhibited the highest creep resistance.
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Role of Cracked Interlayer on Deformation Processing of Al/hard Chrome/Al Laminate
S. Fakher,M. Reihanian,S. M. Lari Baghal,Laleh Fatahi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11
The Al/hard chrome/Al laminate with cracked interlayer was processed by single-pass rolling and accumulative roll bonding(ARB). A micro-cracked hard chrome with the thickness range of 5–15 μm was deposited on the Al layer by the electroplatingprocess. The micro-cracked hard chrome layer was considered as a model material to investigate the deformationprocessing of the metal laminate with a discontinuous interlayer. The layered composite with discontinuous interlayer wasmodeled by finite element analysis. Three configurations of discontinuities, including the longitudinal, transverse, andrectangular pattern, were considered in the interlayer. In agreement with the experiments, the simulation results showedthat during the roll bonding process, the discontinuities that are oriented transversely spread in the rolling direction whilethose that are located longitudinally slightly expand in the transverse direction. The peeling test after the single roll bondingrevealed that the bond strength of the Al/Cr composite with cracked interlayer increased with increasing the thicknessreduction and decreasing the hard chrome layer. The hard chrome layer was gradually fragmented during the ARB processand was distributed in the Al matrix.
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Microstructural Investigation and High Temperature Mechanical Behavior of AXE622 Cast Mg Alloy
A. Habibi Eftekhar,S. Mohsen Sadrossadat,M. Reihanian 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5
The microstructure and high temperature properties of the AXE622 Mg alloy were investigated after the conventional andsemisolid casting processes. The tensile test was conducted at room temperature, and 473 K. Impression creep test was performedat a temperature range of 423–498 K under the stress range of 450–600 MPa. The microstructure of the conventionaland semisolid alloys contains α-Mg dendrites, the eutectic phase, secondary phases including (Mg–Al)2Ca, eutectic Mg17Al12,and Al11RE3. During semisolid processing, coarse dendrites of the α-Mg became fine, globular, and Rosetta shape. Theaverage length of the secondary phases in the semisolid alloy decreased from 4.21 to 2 μm and the average grain size of theα-Mg reduced from 113 to 96 μm. Semisolid processing caused a significant improvement in the tensile and creep resistanceof the AXE622 Mg alloy. The stress exponent for creep was calculated in the range 5.6–7.7 for the conventional alloy andin the range 10.3–11 for the semisolid alloy. The activation energy for conventional and semisolid alloy was determined as71.4 kJ/mol and 78.3 kJ/mol, respectively. It was concluded that the dominant creep mechanism in the conventional alloywas the grain boundary diffusion-controlled dislocation climb, while in the semisolid alloy was the power-law breakdown.
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