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1.
The effect of minor additions of As, Sb and P on phase distribution and corrosion behavior has been studied in brasses. The
alloys investigated were 60Cu–39Zn–1Pb, 48.95Cu–45Zn–5Pb–1Sn–0.05As, 48.90Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb and 48.85Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb–0.05P.
Immersion tests in 1% CuCl2 solution indicated that the addition of As improved corrosion resistance while the combined addition of As + Sb and As + Sb + P
was not beneficial. The hardness increased significantly with the addition of As, Sb and P. Microstructural observations indicated
an increase in β phase fraction in the As, Sb and P containing alloys. X-ray diffraction studies confirmed the formation of
intermetallic compounds in As, Sb and P containing alloys. Based on the microstructural observations, the intermetallic compounds
appear to be primarily precipitated in the β phase with As + Sb and As + Sb + P additions. The lower corrosion resistance
of the alloys 48.90Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb and 48.85Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb–0.05P has been related to increase
in β phase volume fraction and precipitation of intermetallic compounds in the β phase. 相似文献
2.
Evolution of interfacial phase formation in Sn–3.0Ag–0.5Cu/Cu (wt%), Sn–3.0Ag–0.5Cu–0.1Ni/Cu, Sn–3.0Ag–0.5Cu/Cu–15Zn, and
Sn–3.0Ag–0.5Cu–0.1Ni/Cu–15Zn solder joints are investigated. Doping Ni in the solder joint can suppress the growth of Cu3Sn and alter the morphology of the interfacial intermetallic compounds (IMCs), however it shows rapid growth of (Cu,Ni)6Sn5 at the Sn–3.0Ag–0.5Cu–0.1Ni/Cu interface. In comparison with the Cu substrates, the Cu–Zn substrates effectively suppress
the formation of Cu–Sn IMCs. Among these four solder joints, the Sn–3.0Ag–0.5Cu–0.1Ni/Cu–15Zn solder joint exhibits the thinnest
IMC, and only (Cu,Ni)6(Sn,Zn)5 formed at the interface after aging. It is revealed that the presence of Ni acts to enhance the effect of Zn on the suppression
of Cu–Sn IMCs in the SAC305–0.1Ni/Cu–15Zn solder joint. The limited formation of IMCs is related to the elemental redistribution
at the joint interfaces during aging. The Sn–3.0Ag–0.5Cu–0.1Ni/Cu–15Zn joint can act as a stabilized interconnection due to
the effective suppression of interfacial reaction. 相似文献
3.
O. V. Suberlyak V. V. Krasins’kyi I. M. Shapoval O. M. Hrytsenko 《Materials Science》2011,46(5):669-678
We study the influence of concentrations of the components of reactive compositions and the conditions of production and hardening
of phenol-formaldehyde resins with the help of epoxy resins in the presence of polyvinylpyrrolidone on the physicomechanical,
thermal, adhesion, insulation, and anticorrosion properties of the composites. The positive effect of modifications with polyvinylpyrrolidone
and epoxy resin manifests itself within the following ranges of concentrations: 0.5–1 wt.% of polyvinylpyrrolidone and 25–30
wt.% of ED-20 in the presence of 1 wt.% of N, N-dimethylaniline. Thus, the adhesion strength of a glue based on the developed
composition becomes four times higher and constitutes 5–6 MPa; the impact strength, static strength in bending, surface hardness,
and the specific bulk electric resistance of the specimens hardened at 150–160°C for 25–30 min become 1.5–2.5 times higher
and are equal to 5–6J/m2, 15–17 MPa, 350–420 MPa, and (5.5–6.5)⋅1010 Ω⋅m, respectively. The behavior of these characteristics strongly depends on the conditions of hardening. We optimized the
composition of modified phenol-formaldehyde resins, which made it possible to produce materials with predicted properties. 相似文献
4.
J. Ha S. Chae K. W. Chou T. Tyliszczak P. J. M. Monteiro 《Journal of Materials Science》2012,47(2):976-989
This study investigated the effects of organic polymers (polyethylene glycol and hexadecyltrimethylammonium) on structures
of calcium silicate hydrates (C–S–H) which is the major product of Portland cement hydration. Increased surface areas and
expansion of layers were observed for all organic polymer modified C–S–H. The results from attenuated total reflectance–Fourier
transform infrared (ATR–FTIR) spectroscopic measurements also suggest lowered water contents in the layered structures for
the C–S–H samples that are modified by organic polymers. Scanning transmission X-ray microscopy (STXM) results further supports
this observation. We also observed difference in the extent of C–S–H carbonation due to the presence of organic polymers.
No calcite formed in the presence of HDTMA whereas formation of calcite was observed with C–S–H sample modified with PEG.
We suggest that the difference in the carbonation reaction is possibly due to the ease of penetration and diffusion of the
CO2. This observation suggests that CO2 reaction strongly depends on the presence of organic polymers and the types of organic polymers incorporated within the C–S–H
structure. This is the first comprehensive study using STXM to quantitatively characterize the level of heterogeneity in cementitious
materials at high spatial and spectral resolutions. The results from BET, XRD, ATR–FTIR, and STXM measurements are consistent
and suggest that C–S–H layer structures are significantly modified due to the presence of organic polymers, and that the chemical
composition and structural differences among the organic polymers determine the extent of the changes in the C–S–H nanostructures
as well as the extent of carbonation reaction. 相似文献
5.
F. Edler P. Ederer A. C. Baratto H. D. Vieira 《International Journal of Thermophysics》2007,28(6):1983-1992
The objective of the present investigation was the determination of the melting temperatures of the eutectic compounds Fe–C,
Co–C, and Ni–C. Six eutectic fixed-point cells of the Physikalisch-Technische Bundesanstalt (PTB) (Fe–C1, Fe–C2, Co–C1, Co–C2,
Ni–C1, and Ni–C2) and two cells of the Brazilian National Metrological Institute (Inmetro) (Fe–C1V and Ni–C1V), useable for
the calibration of contact thermometers, were investigated. Their melting temperatures were calculated by extrapolation of
the emf-temperature characteristics of four stable Pt/Pd thermocouples, which were calibrated at the eutectic fixed points
and at conventional fixed points of the International Temperature Scale of 1990 (ITS-90). On the basis of the eight eutectic
fixed-point cells and seven independent calibration runs, the melting temperatures of the Fe–C, Co–C, and Ni–C eutectics resulted
in 1153.67 ± 0.15°C, 1323.81 ± 0.27°C, and 1328.48 ± 0.20°C, respectively, with expanded uncertainties corresponding
to a coverage factor of k = 2. 相似文献
6.
The isothermal treatment of the β phase in some Cu-based alloys produces its decomposition by an earlier precipitation of
γ phase. During their growth, by means of a diffusion-controlled process, the precipitates show evidences of morphological
changes. In the first stages and for a Cu–Zn–Al alloy, the morphology is spherical and cuboidal, but develops more complex
shapes such as dendrites, owing to composition fields, interphase overlapping, crystallography characteristics, and relative
orientation. In this work, a dendritic γ precipitate characterization is done and morphological theoretical predictions are
applied, for Cu–Zn–Al and Cu–Al–Be alloys. 相似文献
7.
Influence of granulated blast furnace slag on the reaction,structure and properties of fly ash based geopolymer 总被引:1,自引:0,他引:1
Ground granulated blast furnace slag (GBFS) has been used to alter the geopolymerisation behaviour of fly ash. The influence
of varying amount of GBFS (5–50%) on the reaction kinetics has been studied using isothermal conduction calorimetry. It was
observed that the reaction at 27 °C is dominated by the GBFS activation, whereas the reaction at 60 °C is due to combined
interaction of fly ash and GBFS. The reaction product of geopolymerisation has been characterised using X-ray diffraction
and scanning electron microscopy–X-ray microanalysis. Alumino–silicate–hydrate (A–S–H) and calcium–silicate–hydrate (C–S–H)
gels with varying Si/Al and Ca/Si ratio are found to be the main reaction products. Coexistence of A–S–H and C–S–H gel further
indicates the interaction of fly ash and GBFS during geopolymerisation. Attempt has been made to relate the microstructure
with the properties of the geopolymers. 相似文献
8.
The effect of long-term natural variations in the isotopic composition on the temperature of the reproduction of the triple
point of water – the main reference point of the ITS-90 International Temperature Scale – is investigated.
Translated from Izmeritel’naya Tekhnika, No. 12, pp. 31–33, December, 2008. 相似文献
9.
Two novel titanium alloys, Ti–10V–2Cr–3Al and Ti–10V–1Fe–3Al (wt%), have been designed, fabricated, and tested for their intended
stress-induced martensitic (SIM) transformation behavior. The results show that for Ti–10V–1Fe–3Al the triggering stress for
SIM transformation is independently affected by the β domain size and β phase stability, when the value of the molybdenum
equivalent is higher than ~9. The triggering stress was well predicted using the equations derived separately for the commercial
Ti–10V–2Fe–3Al alloy. For samples containing β with a lower molybdenum equivalence value, pre-existing thermal martensite
is also present and this was found to have an obstructive effect on SIM transformation. In Ti–10V–2Cr–3Al, the low diffusion
speed of Cr caused local gradients in the Cr level for many heat treatments leading even to martensite free zones near former
β regions. 相似文献
10.
X. P. Zhang C. B. Yu S. Shrestha L. Dorn 《Journal of Materials Science: Materials in Electronics》2007,18(6):665-670
Creep and fatigue behaviors of the interconnections soldered by the lead-free Sn–Ag–Cu–Bi solder were investigated at different
elevated temperatures (with the homologue temperature in the range of 0.71– 0.82), with a comparison to that of a traditional
Sn60Pb40 solder. The results show that the lead-free Sn–Ag–Cu–Bi solder shows a superior anti-creep performance over the Sn60Pb40
solder, in terms of a much lower creep strain rate and a vastly elongated creep fracture lifetime; in the secondary creep
regime, the calculated creep-activation energy for two solders is reasonably close to other published data. In addition, it
has also been shown that the joints soldered by the lead-free Sn–Ag–Cu–Bi solder exhibits a superb fatigue property. 相似文献
11.
N. L Tawfik 《Journal of Materials Science》1997,32(11):2997-3000
Continuous uniform ribbons of Al–16 Si, Al–12.5 Si–1 Ni and Al–12.5 Si–1 Mg were prepared by melt spinning. Microhardness
was measured. The as-melt spun values were 1280, 1370 and 1500 MN m-2 which relax on thermal ageing to 700, 700 and 800 MN
m-2 for Al–16 Si, Al–Si–Ni and Al–Si–Mg, respectively. The hardness values of the melt spun ribbons are higher than the as-cast
rods from which the ribbons were produced by a factor ranging from 1.8–2.2 times. Tensile testing at room temperature shows
that the load–elongation curves are linear with a change of slope occurring in some of the specimens. These curves also show
serrations in the case of as-melt spun and the intermediately annealed Al–Si specimens, while no serration was observed in
the fully annealed samples. No serration was observed in the Al–Si–Ni and Al–Si–Mg alloys. UTS values were 420, 270 and 100
MN m-2 for Al–16 Si, Al–Si–Ni and Al–Si–Mg, respectively. These values show that the rapid solidification process improved
the tensile properties significantly in Al–16 Si and Al–Si–Ni alloys while no significant improvement can be detected for
Al–Si–Mg alloy. A discussion is given on hardness relaxation and tensile testing results in terms of silicon precipitation.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
12.
B. B. Straumal O. A. Kogtenkova S. G. Protasova P. Zięba T. Czeppe B. Baretzky R. Z. Valiev 《Journal of Materials Science》2011,46(12):4243-4247
The melting of coarse- and fine-grained Al–Zn–Mg alloys was studied by the differential scanning calorimetry. The asymmetric
shape of the melting curve indicates the heat effect of the grain boundaries (GBs) wetting. The difference between melting
heat of coarse- and fine-grained samples permitted to estimate the GB wetting heat effect per GB unit area. It is ~0.15 J/m2 for the Al–5 wt% Zn–2 wt% Mg alloy and ~1 J/m2 for the Al–10 wt% Zn–4 wt% Mg alloy. 相似文献
13.
This work explores from a theoretical viewpoint the underlying growth mechanisms which govern the formation of the most important
hydration product present in cementitious environments, the so called C–S–H (calcium–silicate–hydrate) gel. Aiming at identifying
the basic building blocks which make up the cementitious C–S–H gel, we have performed ab-initio calculations at the Hartree
Fock (HF) level. Two different growth mechanisms have been identified depending on the amount of Si and Ca ions, which naturally
lead to the appearance of tobermorite-like and jennite-like nano-crystals. 相似文献
14.
The effect of Cu alloying additions on the crystallization of Fe–Si–B alloy was studied. The selected alloys compositions
are Fe77.5Si13.5B9 and Fe76.5Si13.5B9Cu1. By comparing their crystallization temperatures, activation energy of crystallization, phase formation and microstructural
evolution after heat treatment, the effect of Cu alloying additions was determined. It was found that Cu alloying additions
reduced the crystallization temperature as well as the activation energy of the crystallization. Although the phases formed
in both alloys were Fe3Si and Fe3B phases the microstructures were dramatically different: a dendritic microstructure was observed in the case of the Fe–Si–B
alloy, while spheriodal crystals around 100 nm in size were observed in the case of the Fe–Si–B–Cu alloy. Cu alloying addition
increased the saturation magnetization during primary crystallization whereas it decreased the saturation magnetization after
secondary crystallization began. Interestingly, for both alloys the same trends of the magnetization and coercivity measurements
were observed except that the extent of the changes were higher in the case of the Fe–Si–B–Cu alloy than that of the Fe–Si–B
alloy. 相似文献
15.
Liang Zhang Song-bai Xue Li-li Gao Zhong Sheng Guang Zeng Yan Chen Sheng-lin Yu 《Journal of Materials Science: Materials in Electronics》2010,21(6):635-642
For quad flat packages (QFP256), lead-free soldered joints reliability in service is a critical issue. In this paper, soldering
experiments of quad flat package (QFP256) devices were carried out by means of infrared reflow soldering system with Sn–3.8Ag–0.7Cu
and Sn–3.8Ag–0.7Cu–0.03Ce lead-free solders, respectively, and the mechanical properties of micro-joints of the QFP devices
were tested and studied by STR micro-joints tester. The results indicate that the tensile strength of Sn–Ag–Cu–Ce soldered
joints is better than that of Sn–Ag–Cu soldered joints. In particular, the addition of trace Ce to the Sn–Ag–Cu solder can
refine the microstructures and decrease the thickness of the intermetallic compound layer of Sn–Ag–Cu solder alloys. In addition,
the stress–strain response of Sn–Ag–Cu/Sn–Ag–Cu–Ce soldered joints in quad flat packaging was investigated using finite element
method based on Garofalo–Arrhenius model. The simulated results indicate creep distribution of soldered joints is not uniform,
the heel and toe of soldered joints, the area between soldered joints and leads are the creep concentrated sites. The creep
strain of Sn–Ag–Cu–Ce soldered joints is lower than that of Sn–Ag–Cu soldered joints. 相似文献
16.
C. C. Fu J. S. C. Jang L. J. Chang T. Y. Lin C. M. Kuo 《Journal of Materials Science》2007,42(14):5327-5334
The effect of strain rate and environment on the mechanical behavior at different temperatures of the Ni–19Si–3Nb–0.15B–0.1C
alloy is investigated by atmosphere-controlled tensile testing under various conditions at different strain rates and different
temperatures). The results reveal that the Ni–19Si–3Nb–0.15B–0.1C alloy exhibits ductile mechanical behavior (UTS ∼ 1250 MPa,
ε ~ 14%) at temperatures below 873 K under different atmosphere conditions. However, the alloy without boron and carbon addition
shows ductile mechanical behavior only when the sample is tested in vacuum. This indicates that the microalloying of boron
and carbon does overcome the environmental embrittlement from water vapor at test temperatures below 873 K for the Ni–19Si–3Nb
base alloy. However, the boron and carbon doped alloy still suffers from embrittlement associated with oxygen at a medium
high temperature (i.e. 973 K). In parallel, both of the ultimate tensile strength and elongation exhibit quite insensitive
response with respect to the loading strain rate when tests are held at temperatures below 873 K. However, the ultimate tensile
strength exhibits high dependence on the strain rate in air at temperatures above 873 K, decreasing the ultimate tensile strength
with decreasing strain rate. 相似文献
17.
Sn–8Zn–3Bi solder paste was applied as a medium to joint Sn–3.2Ag–0.5Cu solder balls and Cu/Ni/Au metallized ball grid array
substrates at 210 °C. Sn–Ag–Cu joints without Sn–Zn–Bi addition were also conducted for comparison. The shear behavior of
the specimens was investigated after multiple reflow and thermal aging. For each strength test, more than 40 solder balls
were sheared. The shear strength of Sn–Ag–Cu specimens kept constant ranging from 15.5 ± 1.3 N (single reflow) to 16.2 ± 1.0 N
(ten reflows) and the fractures occurred in the solder. Shear strength of Sn–Ag–Cu/Sn–Zn–Bi specimens fell from 15.9 ± 1.7 N
(single reflow) to 13.4 ± 1.6 N (ten reflows). After single reflow, Sn–Ag–Cu/Sn–Zn–Bi specimens fractured in the solder along
Ag–Au–Cu–Zn intermetallic compounds and at Ni metallization. After ten reflows, fractures occurred in the solder and at solder/Ni–Sn–Cu–Zn
intermetallic compound interface. The shear strengths of the Sn–Ag–Cu and Sn–Ag–Cu/Sn–Zn–Bi packages changed little after
aging at 150 °C. Sn–Ag–Cu/Sn–Zn–Bi joints kept higher strength than Sn–Ag–Cu joints. Sn–Ag–Cu joints fractured in the solder
after aging. But the fractures of Sn–Ag–Cu/Sn–Zn–Bi specimens shifted to the solder with aging time. 相似文献
18.
This work is focused on the application of the calculation of phase diagrams method for alloy and heat treatment design. We
analyzed the influence of Zn content on the precipitation of Mg2Sn in Mg–Sn–Zn alloys. A comparison with previous studies in the Mg–Sn–Zn system was made according to the published results
and computational thermochemistry simulations. The phase evolution in the Mg–Sn–Zn system was evaluated for the different
compositions, and the simulations were used for precise alloy and heat treatment design. The composition of the ternary alloy
was set as Mg–8wt%Sn–1.25wt%Zn. The Sn and Zn content was designed and confirmed to be within the α-Mg solubility limit at
the solution treatment temperature. The addition of Zn and the heat treatment applied resulted in the enhancement and refinement
of the Mg2Sn precipitation. Three Vickers micro-hardness maxima were detected: precipitation of metastable Mg–Zn phases, heterogeneous
precipitation of Mg2Sn on the Mg–Zn precipitates, and Mg2Sn precipitation in the α-Mg matrix. The CT simulations were found to be a valuable alloy design tool. 相似文献
19.
In the present study, Al–Si alloys with Si contents of 23, 26, 28 and 31 wt.%, respectively, were modified with a new modifying
agent. The results show that the primary silicon size decreased about 8–10 times after modification. The wear rates of the
modified and heat-treated Al–Si alloys are lower than those of the unmodified and non-heat-treated Al–Si alloys, respectively.
The silicon content in the range of 23–31 wt.% has a significant effect on the wear rates of the same processed Al–Si alloys
(modification and heat treatment). Under the same load, the wear rates of the same processed Al–Si alloys decreased with the
increasing silicon content. The abrasion took place mainly by cutting and partly by ploughing actions for the non-heat-treated
Al–Si alloys, or on the contrary, mainly by ploughing and partly by cutting actions for heat-treated Al–Si alloys. 相似文献
20.
Richard Fourmentin Marie-Noëlle Avettand-Fènoël Guy Reumont Pierre Perrot 《Journal of Materials Science》2007,42(18):7934-7938
The Al–Cr–Zn ternary system is assessed by the CALPHAD method. The solution phases are modelled using the Redlich–Kister formalism.
The ternary intermetallic compounds are described by using the sublattice model. The main intermetallic compound τ1, of the Al–Cr–Zn system, was treated as δ1-FeZn9 solid phase in accordance with its isotype structure. A comparison with experimental phase diagram is also presented. 相似文献