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1.
AbstractThe bond shear test was used to assess the integrity of Sn–0·7Cu and Sn–0·3Ag–0·7Cu lead-free solder alloy drops solidified on copper substrates with smooth and rough surface finishes. Solder alloys solidified on smooth substrates required higher shear force compared to that on rough substrates. Sn–0·3Ag–0·7Cu alloy required higher shear energy than Sn–0·7Cu alloy. Solder alloys solidified on smooth substrate surfaces exhibited complete ductile failure. On rough copper surfaces, solder alloys showed a transition ridge characterized by sheared intermetallic compounds (IMCs) and the presence of dimples. The peak shear strength decreased with increase in contact area of the solder bond on the substrate. Smooth surface and the presence of minor amount of Ag in the solder alloy enhance the integrity of the solder joint. 相似文献
2.
Properties of Mg– xAl–5Sn–0·3Mn alloys ( x?=?1, 3, 6 and 9) prepared by hot extrusion are reported. The orientation relationship between Mg 2Sn precipitate and Mg matrix in Mg–9Al–5Sn–0·3Mn alloy was determined. The yield strength of the as extruded alloys initially decreased with increasing Al content, then increased for Al contents >6 wt-%. These changes are interpreted in terms of the effect of texture, grain size and second phase on the yield strength of the alloys. 相似文献
3.
AbstractThe resistivity and mechanical properties of Cu–Sn alloys with different compositions were explored by casting, normalising, cold work and subsequent annealing treatment. Results indicated that the Cu–Sn alloy had the characteristics of ultrahigh electrical conductivity, when the Sn content was ~0·5 wt-%. Note that the resistivity of the as cast and annealed Cu–0·5 wt-%Sn alloys is 1·55 and 1·26 μΩ cm respectively. 相似文献
4.
Ag–21Cu–25Sn alloy ribbon as a promising intermediate temperature alloy solder (400–600 °C) was prepared by melt spinning technique in this paper. Rare earth La was added into Ag–21Cu–25Sn alloy to refine the microstructures and improve the wettabilities of as-prepared alloy solders. The phase constitutions, microstructures, melting temperatures and wettabilities of selected specimens were respectively tested. The results showed that the dominant phase constitutions of Ag–21Cu–25Sn– xLa alloy ribbons were Ag 3Sn and Cu 3Sn. The grain size of Ag–21Cu–25Sn– xLa alloy decreased with the addition of La increasing. La addition reduced the melting temperatures of Ag–21Cu–25Sn– xLa alloy ribbons, and effectively improved the wettabilities of the alloy ribbons. When the addition of La was 0.5 wt%, the wettability of as-prepared alloy solder achieved the optimal value of 158 cm 2 g −1 under brazing temperature 600 °C and dwell time 15 min. In addition, raising brazing temperature and prolonging dwell time could improve the wettability of Ag–21Cu–25Sn– xLa alloy ribbon. 相似文献
5.
AbstractThe present work is a study of the thermal properties of Mg– xLi–y Al with x= 4, 8 and 12 wt-% and y= 0, 3 and 5 wt-% as a function of temperature in the range 20–375°C. The thermal diffusivity and coefficient of thermal expansion (CTE) have been measured and the thermal conductivity calculated. The thermal diffusivity of all alloys decreases with an increasing content of lithium. The CTE of the single phase alloys Mg–4Li and Mg–12Li has a linear character, and the CTE of Mg–12Li is higher than that of Mg–4Li. The influence of thermal stresses in the two phase alloy Mg–8Li is perceptible in terms of temperature dependence of the CTE. In Mg–4Li–3Al and Mg–4Li–5Al, an influence of the solution of AlLi phase on all the studied thermal properties has been found. 相似文献
6.
AbstractA series of cast Al – Cu – Mg – Ag based alloys with minor cerium additions have been investigated using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. It was found that increasing the cerium content from 0 to 0.45 wt-% increased the tensile strength at the test temperatures of 25°C and 300°C. The high strength of the casting alloys with cerium is attributed to the refined grains and the high density of fine ω precipitates. However, the addition of 0.2 wt-%Ce to the alloy with 0.25 wt-%Ti induced a detrimental effect on the mechanical properties. The cause of this was found to be the formation of the intermetallic compound Al x Ti 6 Ce 3 Cu. 相似文献
7.
This study investigates the effect of the composite addition of Al and Cu on the microstructure, physical properties, wettability, and corrosion properties of Sn–20Bi solder alloy. Scanning electron microscopy and X-ray diffraction were used to identify the microstructure morphology and composition. The spreading area and contact angle of the Sn–20Bi–x (x?=?0, 0.1 wt% Al, 0.5 wt% Cu, and 0.1 wt% Al–0.5 wt% Cu) alloys on Cu substrates were used to measure the wettability of solder alloys. The results indicate that the alloy with 0.1 wt% Al produces the largest dendrite and the composite addition of 0.1 wt% Al and 0.5 wt% Cu formed Cu6Sn5 and CuAl2 intermetallic compounds in the alloy structure. And the electrical conductivity of Sn–20Bi–0.1Al is the best, which reaches 5.32 MS/m. The spread area of the solder alloy is reduced by the addition of 0.1 wt% Al and 0.5 wt% Cu, which is 80.7 mm2. The corrosion products of Sn–20Bi–x solder alloys are mainly lamellar Sn3O(OH)2Cl2 and the corrosion resistance of 0.1 wt% Al solder alloy alone is the best. The overall corrosion resistance of Sn–20Bi–0.1Al–0.5Cu is weakened and the corrosion of solder alloy is not uniform. 相似文献
8.
Lead–tin (Pb–Sn) alloys are the dominant solders used for electronic packaging because of their low cost and superior properties
required for interconnecting electronic components. However, increasing environmental and health concerns over the toxicity
of lead, combined with global legislation to limit the use of Pb in manufactured products, have led to extensive research
and development studies of lead-free solders. The Sn–Ag–Cu ternary eutectic alloy is considered to be one of the promising
alternatives. Except for thermal properties, much research on several properties of Sn–Ag–Cu alloy has been performed. In
this study, five Sn– xAg–0.5Cu alloys with variations of Ag content x of 1.0 mass%, 2.5 mass%, 3.0 mass%, 3.5 mass%, and 4.0 mass% were prepared, and their thermal diffusivity and specific heat
were measured from room temperature to 150 °C, and the thermal conductivity was calculated using the measured thermal diffusivity,
specific heat, and density values. Also, the linear thermal expansion was measured from room temperature to 170 °C. The results
show that Sn–3.5Ag–0.5Cu is the best candidate because it has a maximum thermal conductivity and a low thermal expansion,
which are the ideal conditions to be a proper packaging alloy for effective cooling and thermostability. 相似文献
9.
In this study, Ti15Sn xCu alloys were synthesised using an argon-arc melting and casting method. The as-cast alloy ingot was heat-treated for 2?h at 1000°C and then quenched in water to investigate the effects of heat treatment on the microstructure and corrosion behaviour of the Ti15Sn xCu alloys. In comparison to the heat-treated Ti15Sn alloy, the average size of cellular grains ( dG), the lamellar length ( λL), and the lamellar thickness ( λT) in heat-treated Ti15Sn2Cu alloy were refined by approximately 36, 30, and 36%, respectively. The corrosion behaviour of heat-treated Ti15Sn xCu alloys was made nobler by adding 2?wt-% Cu content. The precipitation of large amounts of nobler (Ti, Sn) 2Cu nanoparticles hindered grain growth, improved the UTS, 0.2YS, microhardness and good corrosion resistance. 相似文献
10.
In the present work, the effects of Sn, Ca additions on thermal conductivity were investigated in as cast Mg–Sn–Ca alloys. The measured values of thermal conductivity of Mg–3Sn– xCa alloys obviously increased from 85.6 to 126.3?W?m ??1?K ??1 with the increasing Ca from 0 to 1.5?wt-%, and then decreased to 98.3?W?m ??1?K ??1 with the 2.5?wt-% Ca. In addition, the thermal conductivity of the Mg–Sn–Ca (Sn/Ca atomic ratio of 1) alloys decreased slightly from 154.2 to 132.1?W?m ??1?K ??1 with the increasing Sn, Ca. Meanwhile, the microstructures of the selected alloys were discussed in detail, suggesting that the solute atoms that caused lattice distortion had greater effect on thermal conductivity compared with the second phases formed in as cast Mg–Sn–Ca alloys. 相似文献
11.
AbstractThe present study was undertaken to investigate the influence of aging temperature on the creep behaviour of Sn–Ag and Sn–Ag–Bi solder alloys at testing temperatures ranging from 333 to 363 K under constant stress of 7·80 MPa. The steady state creep rate was found to increase continuously with increasing aging temperature at all testing temperatures. Results show that addition of Bi to the binary Sn–Ag solder alloy led to a significant increase in the strength and improvement in the creep resistance. The activation energy for the creep process of Sn–Ag and Sn–Ag–Bi solder alloys was found to have an average value of 36 and 45 kJ mol ?1 respectively. This might be characterised by diffusion of Ag in Sn. The microstructure of the aged samples for both alloys examined by X-ray diffraction measurements supported the improvement in the creep resistance for Sn–Ag alloy by adding a small trace of Bi. 相似文献
12.
AbstractThe effects of minor additions of Ce and Y on the as cast microstructure of Mg–3Sn–2Ca (wt-%) magnesium alloy are investigated and compared. Results indicate that adding minor Ce or Y to Mg–3Sn–2Ca alloy does not cause formation of any new phases in the alloy. The as cast Mg–3Sn–2Ca alloy with addition of 0·5 wt-%Ce or Y is still composed of α-Mg, CaMgSn and Mg 2Ca phases. However, after adding 0·5 wt-%Ce or Y to Mg–3Sn–2Ca alloy, not only the formation of CaMgSn phase in the alloy is suppressed but also the CaMgSn phases in the alloy are effectively refined. In addition, adding 0·5 wt-%Ce to Mg–3Sn–2Ca alloy exhibits higher refinement efficiency to the CaMgSn phase in the alloy than adding 0·5 wt-%Y. Further investigations need to be considered in order to understand the difference of minor Ce and Y with regard to the refinement of CaMgSn phase in the Mg–3Sn–2Ca alloy. 相似文献
13.
As-cast and as-extruded Mg–6Li– xAl–0.8Sn ( x?=?0, 1, 3 and 5?wt-%) alloys were prepared. The microstructure and mechanical properties were investigated and discussed. The experimental results show that the Mg–6Li–0.8Sn alloy is composed of three phases: α-Mg, Mg 2Sn and Li 2MgSn. With the addition of Al, the test alloys display typical α-Mg?+?β-Li duplex structures. The new Mg 17Al 12 and LiMgAl 2 phases were found in the Mg–6Li–1Al–0.8Sn alloy. The lamellar-type AlLi phase was formed whereas the Mg 17Al 12 phase disappeared in Mg–6Li–3Al–0.8Sn alloy. The LiMgAl 2 phase vanished in the Mg–6Li–5Al–0.8Sn alloy. The mechanical properties of as-extruded alloys were remarkably improved. The as-extruded Mg–6Li–3Al–0.8Sn alloy exhibited the best mechanical properties, with a yield strength, tensile strength and elongation of 209.8?MPa, 242.6?MPa and 15.5%, respectively. 相似文献
14.
AbstractThe hot deformation behaviour and microstructural evolution of a near- α titanium alloy (Ti–5·6Al–4·8Sn–2Zr–1Mo–0·35Si–0·7Nd) containing 0·06%C or 0·3%C with bimodal or Widmanstätten starting microstructures were investigated using isothermal compression test at strain rates of 0·01–10 s ?1 in the α+ β or β regions. In the α+ β region, both alloys exhibited continuous flow softening. The globularisation of transformed β structure or the recrystallisation of globular α phase took place, which was more remarkable in the 0·3%C alloy. In the β region, both alloys exhibited steady-state flow behaviour. Dynamic recrystallisation of the β phase occurred in the 0·06%C alloy, while was absent in the 0·3%C alloy. Due to the solution hardening of carbon atoms for the phases and the pinning effect of the carbides on grain boundary, the apparent activation energies of the 0·3%C alloy are higher than those of the 0·06%C alloy in the corresponding α+ β or β phase regions. 相似文献
15.
AbstractThe transformation of precipitated phases of Zr 50·5Cu 34·5?xNi 4Al 11Ag x alloy master ingots with Ag substitution of Cu was studied in detail by phase analysis. The precipitated (Zr–Cu) rich phases deteriorate the glass forming ability (GFA) of Zr 50·5Cu 34·5Ni 4Al 11. Two new (Zr–Cu) rich phases, A1 with bcc structure and a?=?0·339 nm and A2 with fcc superlattice structure and a?=?1·21 nm, were identified by a transmission electron microscope. When x?=?2, A1 phase disappears, and A2 phase remains and is suppressed gradually with further Ag addition. When x?=?13, one precipitated phase with Ag more than 13 at-% begins to deteriorate GFA. In the view of chemistry, the precipitation of (Zr–Cu) rich phases means that the interaction between Cu and Zr atoms is rather drastic. The addition of Ag weakens the interaction between Cu and Zr. The similar competition mechanism proposed by the authors plays an important role in suppressing precipitated phases and improving GFAs. 相似文献
16.
AbstractHot rolled Al–6Li–1Cu–1Mg–0·2Mn (at.-%) (Al–1·6Li–2·2Cu–0·9Mg–0·4Mn, wt-%) and Al–6Li–1Cu–1Mg–0·03Zr (at.-%) (Al–1·6Li–2·3Cu–1Mg–0·1Zr, wt-%) alloys developed for age forming were studied by tensile testing, electron backscatter diffraction (EBSD), three-dimensional atom probe (3DAP), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). For both alloys, DSC analysis shows that ageing at 150°C leads initially to formation of zones/clusters, which are later gradually replaced by S phase. On ageing at 190°C, S phase formation is completed within 12 h. The precipitates identified by 3DAP and TEM can be classified into (a) Li rich clusters containing Cu and Mg, (b) a plate shaped metastable precipitate (similar to GPB2 zones/S″), (c) S phase and (d) δ′ spherical particles rich in Li. The Zr containing alloy also contains β′ (Al 3Zr) precipitates and composite β′/ δ′ particles. The β′ precipitates reduce recrystallisation and grain growth leading to fine grains and subgrains. 相似文献
17.
Polycrystalline Cd
x
Cu 1−x
Fe 2−y
Gd
y
O 4 ferrites for y=0·0 and 0·1 were prepared by ceramic technique. X-ray diffractograms of powder samples show cubic symmetry with x⩾0·2 for y=0·0 and 0·1, while compositions with x=0·0 for y = 0·0 and 0·1 are tetragonal. The thermopower measurements for Gd 3+-undoped ferrites in the temperature range 300 K to 788 K show n-type conductivity for x⩾0·2. The substitution of Gd 3+ changed n-type conductivity of the compositions to p-type. The mobilities calculated show decreasing trend on Gd 3+ substitution. The values of activation energy Δ E and drift mobility E
d suggest polaron formation in substituted samples. The conduction mechanism is explained on the basis of localized model and
formation of Gd 3++Fe 2+ stable pairs at B site and Cu 1++Fe 3+ at A site. 相似文献
18.
AbstractThe rapidly solidified (RS) Mg–Zn based alloys with Ce addition were produced via atomising the alloy melt and subsequent splat quenching on the water cooled copper twin rollers in the form of flakes. The effects of Ce additions on the microstructures, phase compositions, thermal stability and isochronal age hardening behaviour of the RS Mg–Zn alloy were systematically investigated. The RS Mg–6Zn alloy is characterised by fine grains in the size of 6–10 μm and is composed of α-Mg, Mg 51Zn 20 and a small quantity of MgZn 2 and Mg 2Zn 3 phases. With the increment of Ce, the microstructures of the alloys are refined, and the volume fractions of dispersions are increased remarkably. The stable intermetallic compounds, i.e. the Mg xZn yCe z ternary phases, are formed in the RS Mg–Zn–Ce alloys at the expense of the Mg 51Zn 20 phases, which leads to the enhanced thermal stability of the alloys, especially for the Mg–6Zn–5Ce alloy. In the alloy, the atomic percentage ratio of Zn/Ce in the Mg xZn yCe z phase is close to two, and the maximum hardness is 91·5±7 HV after annealing at 200°C for 1 h. However, the age hardening behaviour of the alloys decreases with the increment of Ce, and the main reason is discussed. 相似文献
19.
AbstractTwo kinds of ternary Mg based alloys were designed to join the AZ31B magnesium alloy plates by high frequency induction soldering with argon shielding gas. The microstructures and properties of the filler metals and joints were investigated by SEM, X-ray diffraction, differential scanning calorimetry, spreading test and tensile test. The results have shown that the microstructures of Mg–31·5Al–10Sn filler metal mainly consist of Mg 17Al 12, Mg 2Sn and a trace amount of α-Mg phases, while the microstructures of Mg–29·5Zn–1Sn filler metal include α-Mg phase and Mg 7Zn 3 with a trace of α-Mg and Mg 2Sn phases. Both of the filler metals have narrow melting zones; however, the spreading area of the Mg–31·5Al–10Sn filler metal is much larger than that of the Mg–29·5Zn–1Sn filler metal on the AZ31B base metal. The average tensile strength of solder joints with Mg–31·5Al–10Sn filler metal is a little higher than that of the latter solder joints with Mg–29·5Zn–1Sn filler metal. 相似文献
20.
The phenomenon of conversion of the conductivity type in p-type samples of the Cd xHg 1−x Te (0.28≤ x≤0.55) and Zn xCd yHg 1−x−y Te solid solutions bombarded by low-energy argon ions was studied. It is shown that a necessary condition for the conversion effect in Cd xHg 1−x Te with 0.28≤ x≤0.39 is ion neutralization in the bombarding beam. The dependence of the conversion layer thickness in Cd xHg 1−x Te on the solid solution composition agrees with that predicted by the diffusion model of ion-bombardment-induced conversion of the conductivity type. 相似文献
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