Showing 10 results for Intermetallic
M. Shahmiri, S. Murphy,
Volume 5, Issue 4 (12-2008)
Abstract
Abstract: The microstructural features of the early stage of ordering of the intermetallic compound Pt2FeCu have been
examined using optical and transmission electron microscopy in conjunction with X-ray diffraction technique. It was
found that the compound has similar morphological alteration to that of FePt in which the ordering cannot be
suppressed by rapid quenching.
The early stage of ordering transformation was initiated at temperatures above the critical value of 1178 oC, by a
homogeneous nucleation of the intermediate short range ordered particles and ultra rapid directional-induced
heterogeneous growth (burst type). As the result of these combined mechanisms, twin –related ordered domains have
been formed which in turn minimize the strains produced by ordering reaction in polycrystalline material. The
individual grain was divided up by different sizes of twin-related ordered domain bonded with {101} habit planes.
R. Khoshhal, M. Soltanieh, M. Mirjalili,
Volume 7, Issue 1 (3-2010)
Abstract
Abstract:
titanium sheets in pure molten aluminum at 750
and X-Ray Diffraction Analysis results, TiAl
intermetallic layer thickness increases slowly at primary stages. After that an enhanced growth rate occurs due to layer
cracking and disruption. Presumably, reaction starts with solving titanium into the molten aluminum causing in
titanium super saturation and TiAl
intermetallic layer which consequently leads to TiAl
energy of intermetallic layer formation and growth was developed by measuring titanium thickness decreases.
In this work, kinetics of intermetallic compounds formation in Al-Ti system was studied by immersingoC, 850 oC and 950 oC. According to Scanning Electron Microscopy3 is the only phase can form at the interface. Observations revealed that3 formation. At this stage, growth may be controlled by aluminum diffusion through3 formation at the interface of Ti-TiAl3. Furthermore, activation
M. Adeli, M. Shekari, S. H. Seyedein, M. R. Aboutalebi,
Volume 7, Issue 2 (6-2010)
Abstract
Combustion synthesis is a special thermophysico-chemical process applied for production of intermetallic compounds. In the present work, a reaction–diffusion numerical model was developed to analyze the combustion synthesis of aluminide intermetallics by self-propagating high-temperature synthesis process. In order to verify the reliability of the numerical model, an experimental setup was designed and used to perform the combustion synthesis of nickel and titanium aluminides. The developed model was further used to determine the temperature history of a powder mixture compact during self-propagating high-temperature synthesis. The effect of compact relative density on combustion temperature and wave propagation velocity was also studied.
S. Ghafurian, S. H. Seyedein, M. R. Aboutalebi, M. Reza Afshar,
Volume 8, Issue 3 (9-2011)
Abstract
Abstract: Microwave processing is one of the novel methods for combustion synthesis of intermetallic compounds and
composites. This method brings about a lot of opportunities for processing of uniquely characterized materials. In this
study, the combustion synthesis of TiAl/Al2O3 composite via microwave heating has been investigated by the
development of a heat transfer model including a microwave heating source term. The model was tested and verified
by experiments available in the literature. Parametric studies were carried out by the model to evaluate the effects of
such parameters as input power, sample aspect ratio, and porosity on the rate of process. The results showed that
higher input powers and sample volumes, as well as the use of bigger susceptors made the reaction enhanced. It was
also shown that a decrease in the porosity and aspect ratio of sample leads to the enhancement of the process.
M. R. Parsa, M. Soltanieh,
Volume 9, Issue 2 (6-2012)
Abstract
In this research, the nickel oxide was dissolved in cryolite at temperatures of 880, 940 and 1000°C. In order to reduce the nickel oxide, aluminum was added to the salt. Simultaneously the nickel oxide was reduced and Al3Ni2 intermetallic compound was formed. In the duration intervals of 2.5-40 minutes samples of the salt and metallic phases were taken. The variation of the nickel content in metallic and salt samples was determined by the AAS. The results indicate that increasing the temperature and duration has a positive effect on the reduction process and Al3Ni2 intermetallic compound formation. The nickel content in the metallic sample has its highest amount at 1000°C in 10 minutes. Furthermore, practical results of the studies of nickel content variations in metallic and salt samples confirm the data obtained from theoretical calculations.
F Foadian, M Soltanieh, M Adeli, M Etminanbakhsh,
Volume 11, Issue 4 (12-2014)
Abstract
Metallic-intermetallic laminate (MIL) composites are promising materials for structural applications especially in the aerospace industry. One of the interesting laminate composites is the Ti-TiAl 3 multilayer. In this work, commercially pure sheets of aluminum and titanium with almost equal thickness of around 0.5 mm were explosively joined. The achieved multilayers were annealed at 630 ℃in different times so that an intermetallic layer was formed at the Ti/Al interface. The resulting microstructure was studied by optical and scanning electron microscopy and Energy Dispersive Spectroscopy (EDS). TiAl3 was the only intermetallic phase that was observed in all annealing times. The kinetics of the formation of TiAl 3 was investigated and compared to previous research studies performed on Ti-Al multilayers which were fabricated using methods other than explosive welding.
K. Tavighi, M. Emamy, A. R. Emami,
Volume 11, Issue 4 (12-2014)
Abstract
This study was undertaken to investigate the effects of Cu and solution heat treatment on the microstructure and hardness of cast Al-Al4Sr metal matrix composite. Different amounts of Cu (0.3, 0.5, 1, 3 and 5 wt.%) were added to the composite. Specimens were heat treated at 500 °C for 4 hours followed by water quenching. Microstructural studies were assessed by the use of optical microscope, scanning electron microscope (SEM) and x-ray diffractometry (XRD). The results showed that addition of 5 wt.% Cu reduces the length of large needle-like Al4Sr phase and refines the microstructure. In addition, the presence of Cu-intermetallics increases hardness of the composite. Cu mainly forms θ phase which segregates at the grain boundaries. Heat treatment partially dissolves Cu-intermetallics and homogenizes the distribution of θ phase in the matrix.
A. Shabani, M. R. Toroghinejad, A. Shafyei,
Volume 13, Issue 2 (6-2016)
Abstract
In the present study, the effect of post-rolling annealing heat treatment on the formation of intermetallic compounds between Al-Cu strips, in the presence of nickel coating on the Cu strips, was investigated. In addition, the effect of post-rolling annealing and intermetallic compounds on the bond strength of Al-Cu strips was evaluated. In order to prepare samples, Cu strips were coated with nickel by electroplating process. After surface preparing, Cu strips were placed between two Al strips and roll bonded. This method is used for producing Al-Ni-Cu composites. Then the samples were annealed at 773K for 2 h. The formation of intermetallic compounds was studied using energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Also, in order to investigate bond strength of Al-Cu after post-rolling annealing heat treatment, samples were produced using nickel powder and nickel coating. Then bond strength of strips was investigated using peeling test. The results revealed that by post-rolling annealing of layers, the bond strength between Al-Cu strips decreases dramatically.
M. H. Zamani, M. Divandari, M. Tamizifar,
Volume 15, Issue 1 (3-2018)
Abstract
Lap joints of commercially pure magnesium plates to aluminium plates (Magnesium plate on the top, and Aluminium plate, grade 1100, on the bottom side) were conducted by friction stir welding using various traveling and rotation speeds of the tool to investigate the effects of the welding parameters on the joint characteristics and strength. Defect-free lap joints were obtained in the welding traveling speed range of 40-80 mm/min, and rotational speed range of 1200-1600 rpm. The shear tensile strength of Mg/Al joints increased as a result of decreasing the welding speed from 120 to 40 mm/min at constant rotation speed of 1600 rpm. Defects such as surface grooves, excessive flash, tunnels, and voids were observed if the joints prepared out of the mentioned range. The effects of the welding parameters are discussed metallographically based on observations with optical and scanning electron microscopes.
B. Sharif, H. Saghafian, H. Razavi,
Volume 15, Issue 2 (6-2018)
Abstract
In the present research, thixoforming route was carried out in order to enhance the microstructural features of LM28 piston alloy. Typical microstructure of this alloy was composed of coarse, polygonal primary silicon particles, eutectic matrix and intermetallic phases. Thermal analysis was carried out to study the solidification path of the base alloy and determine the major arrest temperatures of metallurgical reactions. Continuous and iso-thermal mechanical stirring were utilized to produce non-dendritic LM28 alloy feedstock for further processing. The rheocast samples were subjected to a rotation speed of 450 rpm. The slugs machined from the solidified rheocast specimens were heated in the mushy zone temperature and then were thixoformed via a laboratory press. The thixoformed specimens show a relatively homogenous microstructure and present no evidence of porosities. Fine, blocky primary silicon and Fe-rich intermetallic particles were uniformly distributed in the matrix of LM28 alloy. Optical microscope and scanning electron microscope linked with EDX were used to investigate the microstructure of specimens
