Sn Binary Alloys Research Articles

Effects of melt flow on the primary dendrite spacing of Pb–Sn binary alloy during directional solidification

The influences of melt flow generated by traveling magnetic fields (TMFs) on dendrite growth during the upward-directional solidification of Pb–33 wt% Sn binary alloy were investigated under the condition of 1× g gravity. When the direction of the TMF was changed from upward to downward, the primary dendrite spacing gradually increased, and the peak of distribution of the primary dendrite spacing shifted to the narrower values. This was caused by the different intensities of melt flow, which was controlled by TMFs. The effects of TMFs on melt flow were similar to those of adjustments in gravity levels; thus, the primary dendrite spacing varied. The effective gravity acceleration, which was used to modulate melt flow, decreased for downward-TMFs and increased for upward-TMFs. As the drawing speed increased, the modulated flow showed more significant influences on primary dendrites spacing.

Solid solution strengthening in polycrystals of Mg–Sn binary alloys

Solid solution effects on the hardness and flow stress in Mg–Sn binary alloys with Sn content between 0.18% and 2.18% at temperatures ranging from ambient to 623 K were investigated in this study. At room temperature, the hardness increases with the Sn content as H v0.5 = 28.3 + 6.88 c, the 0.2% proof strength (corrected for grain size strengthening effect) and c n follow a linear relationship, where c is the solute atom fraction and n = 1/2 or 2/3. The results suggest that the strengthening of basal planes controls the solid solution strengthening in polycrystals of Mg–Sn binary alloys. However, the c n power-law is not applicable in the temperature range from 423 K to 623 K, which is proposed to be ascribed to the competition between solid solution strengthening and softening effect.

Microstructure, tensile properties and compressive creep resistance of Mg-(5–8.5)%Sn-2%La alloys

The microstructure, tensile properties and compressive creep resistance of permanent-mould cast Mg-(5–8.5)%Sn-2%La (mass fraction) alloys were investigated. The results show that Mg-(5–8.5)%Sn-2%La alloys are all composed of α-Mg phase, Mg 2Sn and Mg-La-Sn compounds. Compared with those of Mg-5%Sn binary alloy, the grain size and the content of Mg 2Sn compound in Mg-5%Sn-2%La alloy are decreased. With the increase of Sn content in Mg-(5–8.5)%Sn-2%La alloys, the content of Mg 2Sn compound increases, while that of Mg-Sn-La compound changes little. In addition, the investigation suggests that the thermally stable Mg-Sn-La and Mg 2Sn compounds can improve the tensile properties and compressive creep resistance of the alloys.

Characteristics and heat treatment of cold-sprayed Al–Sn binary alloy coatings

In this study, Al–Sn binary alloy coatings were prepared with Al–5 wt.% Sn (Al–5Sn) and Al–10 wt.% Sn (Al–10Sn) gas atomized powders by low pressure and high pressure cold spray process. The microstructure and microhardness of the coatings were characterized. To understand the coarsening of tin in the coating, the as-sprayed coatings were annealed at 150, 200, 250 and 300 °C for 1 h, respectively. The effect of annealing on microstructure and the bond strength of the coatings were investigated. The results show that Al–5Sn coating can be deposited by high pressure cold spray with nitrogen while Al–10Sn can only be deposited by low pressure cold spray with helium gas. Both Al–5Sn and Al–10Sn coatings present dense structures. The fraction of Sn in as-sprayed coatings is consistent with that in feed stock powders. The coarsening and/or migration of Sn phase in the coatings were observed when the annealing temperature exceeds 200 °C. Furthermore, the microhardness of the coatings decreased significantly at the annealing temperature of 250 °C. EDXA analysis shows that the heat treatment has no significant effect on fraction of Sn phase in Al–5Sn coatings. Bonding strength of as-sprayed Al–10Sn coating is slightly higher than that of Al–5Sn coating. Annealing at 200 °C can increase the bonding strength of Al–5Sn coatings.

Cold spraying of Al–Sn binary alloy: Coating characteristics and particle bonding features

In this study, Al–Sn binary alloy coatings were prepared with Al–10 wt.% Sn (Al–10Sn) and Al–20 wt.%Sn (Al–20Sn) gas atomized alloy powders by low pressure cold spray process. The microstructure and microhardness of the coatings were characterized. The deposition efficiency of Al–Sn and pure aluminum powder were tested on sand blasted substrates of Al6061, copper and SUS304. To investigate the particle bonding features of Al–10Sn powder, the wipe test was carried out on polished substrate surfaces. The average critical velocity of Al–Sn alloy powders was estimated combining with the deposition efficiency. The results proved that Al–Sn coatings with dense and uniform structure can be deposited successfully by low pressure cold spray with helium as the propellant gas. The weight content of tin in Al–Sn coating is 12% and 22% for Al–10Sn and Al–20Sn coating, respectively. With the increase of tin content in feedstock powder, the as-sprayed coatings present similar microhardness of 73 and 74 for Al–10Sn and Al–20Sn while, on the other hand, the deposition efficiency decreased. Bonding features of Al–10Sn particles indicated that the melting of tin phase occurred on the contact interface during particle impacting. This melting of tin phase and low strength of tin may affect the particle bonding process and hence increase the critical velocity for Al–Sn binary alloy powders.

Effect of Ca addition on precipitation in the Pb-4 wt.% Sn alloy

Abstract The precipitation behaviour of Pb-4 wt.% Sn alloys containing 0.001–0.088 wt.% Ca has been mainly studied by resistivity measurements and transmission electron microscopy. The addition of Ca to the Pb–Sn binary alloy suppresses the discontinuous precipitation and accelerates the formation of continuous precipitates with a high coherency. Therefore, the addition of Ca induces a higher age hardening. TEM observations reveal that the continuous precipitates in the Ca-doped alloys contain Pb, Ca, and Sn, and have an L12-type ordered structure. The discontinuous precipitation reaction in the Pb-4 wt.% Sn–Ca alloys is suppressed by the formation of continuous precipitates and, furthermore, the segregation of the solute elements at the grain boundaries.

Low temperature coefficient of resistivity Ag–Cd and Ag–Sn alloys—structure and transport

The microstructure vis-a-vis electrical transport behavior of Ag–Cd and Ag–Sn binary alloys in the temperature range 70–300 K has been studied. The 22.2 wt.% Cd and 29.4 wt.% Cd alloys were both found to have a single-phase structure made of solid solution of Ag. The lattice parameter however increased with increasing Cd content in the alloy. The microstructure of 17.7 wt.% Sn and 23.5 wt.% Sn alloys however is made of two phases Ag 4Sn and Ag 3Sn. The resistivity of Ag–Cd alloys increased with increasing Cd content and the temperature coefficient of resistivity (TCR) decreased to 1560 ppm K −1 for the 29.4 wt.% Cd alloy compared to 4100 ppm K −1 for pure Ag. The lowest TCR however was obtained for the 17.7 wt.% Sn alloy, 375 ppm K −1, which has a room temperature resistivity of 23.93 μΩ cm.

Yield of hydrogen during cathodic polarisation of Al–Sn alloys

The results presented in this paper were obtained with three Al–Sn binary alloys (0.09, 0.2 and 0.4 wt.% Sn, respectively) that had been prepared on super pure (99.999%) Al base. The yield of hydrogen evolved during cathodic polarisation of Al–Sn alloys in a 2 M NaCl solution was measured volumetrically as a function of current density, temperature and tin content in the alloy. The yield was established to be somewhat below 2 at all current densities and at low temperatures, while with increasing temperature it approached the value of 4. With the increase of tin content in the alloy, the yield of hydrogen decreases, which depends on the degree of hyperactivity that occurs in Al–Sn alloys in the region of high cathodic potentials.

Peculiarities of the electrical double layer structure on mechanically renewable electrodes of Ag–Sn alloys in aqueous solutions of surface-inactive electrolytes

The behavior of electrodes of Ag–Sn binary alloys (Sn content from 3 to 9 at.%; the range of solid solutions of Sn in Ag) renewable by cutting was studied in aqueous NaF solutions by using the impedance method. Upon the electrode surface renewal under potentiostatic conditions in the ideal polarizability range, quick changes in the differential capacitance of the electrical double layer were observed. These changes show that the content of tin atoms in the surface layer increases with the exposure of the renewed surface to the solution, i.e. tin is the surface-active component of the alloy. Within the framework of known phenomenological models of the structure of the electrode ∣ solution interface, a mechanism is put forward based on the analysis of the time effects observed and the experimental results obtained on the behavior of Ag 3Sn intermetallic compound in contact with aqueous NaF solutions. This mechanism allows the processes, which occur in the metal phase during the formation of the equilibrium alloy ∣ electrolyte interface, to be interpreted qualitatively. The mechanism involves two stages: (1) quick diffusion of the surface-active component of the alloy (Sn) to the surface and (2) a slower stage associated with the formation of an intermetallic-like compound Ag 3Sn in the surface layer.

Specific features of the structure of electrical double layer on mechanically renewed Ag-Sn electrodes in aqueous surface-inactive electrolytes

The behavior of an Ag–Sn binary alloy (3–9 at. % Sn; region of solid solutions of Sn in Ag) in aqueous NaF solutions is studied with the aid of an impedance method. After the electrode surface renewal in potentiostatic conditions in the region of ideal polarizability, the EDL differential capacitance rapidly changes with time. These changes testify that the content of tin atoms in a surface layer increases with the duration of contact between a renewed surface and the solution, i.e. tin is a surface-active component of the alloy. On the basis of an analysis of the observed time effects in the framework of available phenomenological models for the electrode/solution interface and the experimental data obtained earlier for an Ag3Sn electrode in aqueous NaF solutions, a mechanism is suggested, which allows one to qualitatively interpret the formation kinetics of an equilibrium interface between alloys under study and the electrolyte, which occur in the metallic phase. The mechanism includes two stages: (1) a fast escape of atoms of the surface-active component of the alloy (Sn) into a surface layer, and (2) a slower stage of the formation of intermetallic compound Ag3Sn in a surface layer.

Creep deformation of Pb–Sn–Zn ternary alloys

The steady state creep of Pb–65Sn–1Zn and Pb–65.5Sn–3.4Zn ternary alloys was investigated in the temperature range from 353 to 413 K under different constant stresses. The results of creep characteristics show two deformation regions (below and above 383 K). The strain rate sensitivity parameter ( m) has been found to increase by increasing the working temperature up to about 0.53 and 0.64 for the first and second alloys, respectively. The activation energies of steady state creep of the first and second alloys have been found to be 41–59.7 and 40–58 kJ mol −1, respectively, characterising grain boundary diffusion. Metallographic observations and X-ray analysis have been confirmed that grain boundary sliding (GBS) accommodated by dislocation motion is the important mode of deformation. It was also established that Pb–Sn–Zn ternary alloys show superior superplastic behaviour compared with Pb–Sn binary alloys as a result of its lower melting temperature ( T m), finer grain size, and the multiplicity of types of interphase boundaries.

Activity Measurement of the Constituents in Molten Ag-In-Sn Ternary Alloy by Mass Spectrometry

Activities of the constituents in one of the Pb-free solder systems, Ag–In–Sn, were studied experimentally using a mass spectrometer. Ion current ratios of Ag to In were measured in the temperature range 1273–1523 K . From the experimental results and the assessed thermodynamic properties of molten Ag–Sn, Ag–In, and In–Sn binary alloys, the excess Gibbs energy of liquid Ag–In–Sn ternary alloy was determined.

Defect structure development in electron-irradiated Cu-based Si, Ge and Sn binary alloys

Abstract Systematic experiments of 1 MeV electron irradiation were made on Cu-based binary alloys above 300 K using a high-voltage electron microscope in order to study the effects of solute atoms on defect structure development. The solute elements examined were Si (+5.08%), Ge (+27.77%) and Sn (+83.40%), the volume size factors of which are given in parentheses; the amounts of these were 0.05, 0.3 and 2 at.% respectively. Interstitial-type dislocation loops and stacking-fault tetrahedra (SFTs) were formed in pure Cu and all the alloys. In pure Cu, the temperature dependence of the loop number density had a ‘down peak’ (i.e. loops hardly formed) around 373 K; below this temperature the majority of the loops shrank and disappeared during irradiation, while all the loops grew larger above it; and SFTs were unstable and repeated the formation and disappearance. In the alloys, the loop number density decreased monotonically with increasing temperature (no down peak was observed); loop formation was greatly e...

Defect structure development in electron-irradiated Cu-based Si, Ge and Sn binary alloys

Defect structure development in electron-irradiated Cu-based Si, Ge and Sn binary alloys

Effect of solute convection on the primary arm spacings of Pb–Sn binary alloys during upward directional solidification

In this article, in order to investigate the effect of solute convection on the primary arm spacings of Pb–Sn binary alloys, upward directional solidification experiments have been carried out under the condition of 1× g. The primary arm spacings have been measured with the increase of fraction solidified. Results show that the primary arm spacings of hypoeutectic Pb–Sn binary alloy changed with increase of fraction solidified and the peak of distribution of primary arm spacings was shifted to the field of the narrower spacings with the increase of fraction solidified. It has been noted that the average of spacings decreased with the increase of fraction solidified. Mechanism of tip splitting of primary dendrite arm was found to be responsible for the change of the primary arm spacings with the increase of fraction solidified.

Effect of Solidification Rate and Temperature Gradient on the Changes of Mushy Zone Length in Pb-36mass%Sn Binary Alloys during Upward Directional Solidification.

Upward directional solidification experiments have been carried out on Pb-36mass%Sn binary alloys with varying the solidification rate and temperature gradient. Results show that due to solute convection, the length of the mushy zone was not constant even when the dendritic growth at a constant temperature gradient was maintained during upward directional solidification. The length of the mushy zone decreased with increasing fraction solidified if solute convection occured. At a constant solidification rate, the greater the temperature gradient is, the greater the change of length of mushy zone is. At a constant temperature gradient, the smaller the solidification rate is, the greater the change in length of the mushy zone is. Effect of solute convection on the length of the mushy zone during upward directional solidification is responsible for the composition change of Sn at ahead of the mushy zone. If the composition at ahead of the mushy zone changes greatly as increasing the fraction solidified, the change of length of the mushy zone is greater.

Measurements of Primary Dendrite Arm Spacings in Directionally Solidified Pb–Sn Binary Alloys

Measurements of Primary Dendrite Arm Spacings in Directionally Solidified Pb–Sn Binary Alloys

Cathodic polarization of Al–Sn alloy in sodium chloride solution

The results presented in this paper were obtained with two Al–Sn binary alloys (0.02 and 0.4 wt% Sn) which had been prepared on super pure (99.999%) Al base. A study of behaviour of these alloys at cathodic polarization in 2 M NaCl solution by means of electrochemical methods complemented by SEM and EDAX analysis provided an insight into the effect of addition of tin on the electrochemical behaviour of aluminium. It has been observed that a low tin content causes aluminium to behave hyperactively at high negative potential values, which leads to crevice formation and conditions favourable for further dissolution. The result of the change of potential in the negative direction with the alloy containing 0.4 wt% tin is superactivation of aluminium as consequence of de-filming processes.

Study of the oxidation of gold-tin preforms using x-ray photoelectron spectroscopy

This study uses x-ray photoelectron spectroscopy (XPS) to investigate the nature of the oxide formed on clean Au–Sn binary alloys (ζ and δ phases) and on preforms with the eutectic composition (29 at % Sn) at low O2 pressures (<10−3 Torr) and at high O2 pressures (up to one atmosphere) at temperatures ranging from room temperature to 200 °C. Sn Auger parameters and XPS angular-resolved data were obtained in addition to the core binding energies to identify the oxide layer. The oxidation of the Au–Sn alloys is basically similar to the oxidation of metallic Sn. The Auger parameter indicates that with low-pressure oxidation a layered oxide structure is formed consisting of SnO and a slightly tin-rich oxide at the interface. Probably a thin skin of Sn(IV) oxide exists on the outer surface of the low-pressure oxide. High-temperature and low-pressure promotes the growth of SnO. As the pressure is increased the Sn(IV) oxide grows more noticeably and with high-pressure oxidation the Sn(IV) oxide grows thicker than the Sn(II) oxide at the interface. The Sn(II) oxide at the interface appears similar to the Sn(II) oxide structure formed at low pressure. The Auger parameter indicates that the Sn(IV) oxide possesses a structure different than that of Cassiterite.

Surface Tension of Liquid Fe–(Cu, Sn, Cr) and Ni–(Cu, Sn) Binary Alloys

Surface Tension of Liquid Fe–(Cu, Sn, Cr) and Ni–(Cu, Sn) Binary Alloys