X-ray diffraction studies of the decomposition and microstructural characterization of cold-worked powders of Cu–15Ni–Sn alloys by Rietveld analysis (original) (raw)
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A study of precipitation in a Cu15 wt%Ni8 wt%Sn alloy
Journal of Materials Science Letters, 1999
The precipitation sequence in Cu-Ni-Sn alloys has been studied in several works . The results of these works have shown that the phase separation occurs spinodally in the early stage of the aging process. The decomposed phases are Sn-rich (α 1 ) and Sn-lean (α 2 ) phases, which have been reported difficult to be analyzed by transmission electron microscope (TEM) . Furthermore, it has been reported that the spinodal decomposition in a Cu-15 wt %Ni-8 wt %Sn alloy occurred only at aging temperatures below 723 K [3]; however, this result was concluded from samples aged for times as long as 10 min. This aging time seems to be too long to study the spinodal decomposition at the early stages, which may take place even during the quenching of solution treated samples. The purpose of this work is to study the early stages of phase separation in a Cu-15 wt %Ni-8 wt %Sn alloy aged at 673, 773 and 873 K for different periods of time, using X-ray diffraction analysis, as well as a field ion microscope, FIM, which has been shown to be an effective tool to study the phase separation at an early stage in different alloy systems.
Effect of Ni Content on Microstructure and Characterization of Cu-Ni-Sn Alloys
Materials (Basel, Switzerland), 2018
Cu-xNi-5Sn (wt %) alloys with a different Ni content were prepared by a powder metallurgy method. The effect of Ni content on the hardness and yield strength of Cu-xNi-5Sn (wt %) alloys was investigated. The microstructure, composition, and morphology of Cu-xNi-5Sn (wt %) alloys were observed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and cold field emission scanning electron microscope (FESEM), respectively. Results indicate that the hardness and yield strength firstly increase and then decrease with the increase of Ni content and reach up to a maximum when Ni content is 12.5 wt %. Furthermore, the formation of the sandwich structure and needle-like phase is found in the grain, the grain boundary and intragranular precipitates are rich in both the Ni and Sn phase. The formation of the inerratic and suitable lamellar precipitates of sandwich structure and needle-like phase can be responsible for the good mechanical prope...
X-ray diffraction analysis of cold-worked Cu-Ni-Si and Cu-Ni-Si-Cr alloys by Rietveld method
Transactions of Nonferrous Metals Society of China, 2011
Cold worked and annealed supersaturated Cu-2.65Ni-0.6Si and Cu-2.35Ni-0.6Si-0.6Cr alloys were studied. The microstructural parameters evolution, including crystallite size, root mean square strain and dislocation density was analyzed using Materials Analysis Using Diffraction software (MAUD). The parameters for both alloys have typical values of cold deformed and subsequently annealed copper based alloy. A net change of the crystallite size, root mean square strain and dislocation density values of the alloys aged at 450 °C for 2.5−3 h seems corresponding to the recovery and recrystallization processes. Addition of Cr as quaternary element did not lead to any drastic changes of post deformation or ageing microstructural parameters and hence of recovery-recrystallization kinetics.
Acta Materialia, 2008
The morphologies and orientation relationships of Cu 6 Sn 5 grains formed between Sn and (0 0 1), (0 1 1), (1 1 1) and (1 23) Cu single crystals under liquid-and solid-state aging conditions were systematically investigated. The regular prism-type Cu 6 Sn 5 grains formed on (0 0 1) and (1 1 1) Cu single crystals are elongated either along two perpendicular directions or along three preferential directions with an angle of 60°between each pair of directions. The orientation relationships between Cu and Cu 6 Sn 5 lattice structures were determined by electron backscatter diffraction and were explained in terms of their minimum misfit. However, on (0 1 1) and (1 2 3) Cu single crystal surfaces, the Cu 6 Sn 5 grains were mainly scallop-type, with only a few regular prism-type grains. Furthermore, the regular prism-type Cu 6 Sn 5 grains will change into scallop-type after long reflow or aging times. Meanwhile it is considered that the growth of the scallop-type grains is supplied by two fluxes: the flux of the interfacial reaction and the flux of ripening. However, the growth of the prism-type grains is only supplied by the flux of the interfacial reaction. The kinetics of IMCs growth between Sn and Cu single crystals was also investigated.
Structural evolution in the solidification process of Cu–Sn alloys
Journal of Non-crystalline Solids, 2007
The liquid structures in the solidification process of the Cu 100Àx Sn x (x = 10, 20, 30, 40) alloys were investigated by X-ray diffraction method. The results show that the Cu 3 Sn and quasi Cu 3 Sn structures exist in the Cu-Sn liquids. Which arouses an obvious structure change indicated by the correlation radius r c at about 900°C. In addition, the structure change induced by the liquid-solid transition at about 30-40°C below the liquidus is also observed.
Significant effect of orientation on Cu6Sn5 coarsening behavior in isothermal aging process
Journal of Materials Science: Materials in Electronics, 2020
Intermetallic compound (IMC) formed on (001) and (111) Cu single crystal has strong orientation and texture characteristics. The special interface morphology and uniform orientation provide a direction for the regulation of IMC growth behavior. In this study, the significant effect of orientation on Cu 6 Sn 5 growth behavior in isothermal aging process was investigated. Synchrotron radiation technology and high pressure air blowing methods were employed to obtain the growth kinetics and the morphology of Cu 6 Sn 5 during the heat preservation stage. The results indicate that scallop-like Cu 6 Sn 5 grains were formed in heat preservation stage. These grains exhibited an abnormal coarsening behavior that their average diameter at a high temperature of 300°C was smaller than that at a low temperature of 250°C after aging for 30 min. Besides, the growth orientation and kinetic controlling factor of these interfacial Cu 6 Sn 5 also changed with the increase of reaction time, which was closely related to the appearance of the abnormal coarsening phenomenon. These results are significant and meaningful to the electronic packaging industry.
EFFECT OF COOLING RATE ON STRESS-STRAIN BEHAVIOUR AND MICROSTRUCTURE OF A CU- ZN- SN ALLOY
The effect of cooling rate on stress-strain behaviour and microstructure of Cu-11.89% Zn-7.68% Sn alloy was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), compression test. In this study, analysis results of the samples cooled in two different types (rapidly cooled in iced-brine and slowly cooled in furnace by homogenization in 750 o C have been evaluated. As a result of SEM observations, dendrite structures are observed in rapidly cooled sample and also dendrites together with annealing twins are observed in slowly cooled sample. From the XRD analysis of samples, two different phases (α-Cu and α-CuSn) have occurred and the sample cooled slowly has been indicates to give more intense peaks. The stress-strain curves obtained from compression tests of samples have been changing. When the alloy was cooled rapidly after heat-treatment, the yield strength is observed to increase and the reason of increase is linked to the increase of defect density as a result of fast cooling.
Microstructural simulation of phase decomposition in Cu–Ni alloys
Journal of Alloys and Compounds, 2008
The microstructure simulation of spinodal decomposition was carried out in the aged Cu-70 and 90 at.% Ni alloys, based on a solution of the non-linear Cahn-Hilliard partial differential equation by the finite difference method. The calculated concentration profiles were compared with the experimental ones determined by atom-probe field ion microscope analyses of the solution treated and aged Cu-70 at.% Ni alloy samples. Both the numerically simulated and experimental results showed a good agreement for the concentration profiles and microstructure evolution in the aged Cu-Ni alloys. A very slow growth kinetics of phase decomposition was observed to occur in this type of alloy. The morphology of decomposed phases consists of an irregular shape with no preferential alignment in any crystallographic direction. The wavelength of composition modulation was determined numerically to be about 2 nm and it remained constant after aging at 573 K for times as long as 8889 h. No phase decomposition was observed to occur for the numerical simulation of aging at temperatures lower than 523 K for a time as long as 1 year.