Combined Addition Of Ag Research Articles

Influences of Ag and In Alloying on Microstructure and Mechanical Properties of Sn-58Bi Solder

Ag (2.0 wt.%) and In (1.5 wt.%) were alloyed into Sn-58Bi eutectic solder, and the individual and combined influences of Ag and In on the microstructure, microhardness, and impact toughness of the SnBi solder were investigated. The results reveal that the microstructures of the SnBiAg, SnBiIn, and SnBiAgIn alloyed solders are coarser than that of the SnBi eutectic solder. Fine Ag3Sn particles are formed in the SnBiAg and SnBiAgIn solders, while small regions of In-rich phases appear in the SnBiIn and SnBiAgIn solders. The microhardness of the three alloyed solders are higher than the SnBi solder, and the Sn-rich phases in the alloyed solders show higher nanohardness, while the nanohardness of the Bi-rich phases with Ag and In addition changes little. The impact toughness of the SnBiAg, SnBiIn, and SnBiAgIn solders are observed to be higher than the SnBi solder, especially in the case of the SnBiAgIn solder. The improvement in ductility of the Sn-rich phase induced by the In solution, and the strengthening effect from the Ag3Sn particles are predicated to be the reason for the increase in impact toughness. The fracture surfaces demonstrate that plastic deformation of the SnBiAgIn solder during the impact process is more obvious. Overall, the combined addition of Ag and In can increase the microhardness and impact toughness of SnBi eutectic solder.

The role of Ag, Ca, Zr and Al in strengthening effects of ZK series alloys by altering G.P. zones stability

The density of precipitates is the most important factor in the strengthening effects of alloys by aging. We here use first-principles calculation to reveal the mechanism of increasing density of precipitates by adding alloying elements for Mg-Zn alloys. The Guinier-Preston (G.P.) zones, which begin to occur during the early stage of precipitation, play an important role in the strengthening of the Mg-Zn alloys. To reveal the mechanism of formation of G.P. zones in Mg-Zn alloys with different alloying elements, we have undertaken systematic calculations to investigate the influence of Ag, Ca, Zr and Al on the stability of G.P. zones in Mg-Zn alloys. We find that the formation energies of Zn G.P. zones with Ag and Ca are much lower than that of pure Zn G.P. zones, while the formation energies of Zn G.P. zones with Zr and Al are slightly higher than that of pure Zn G.P. zones. It indicates that the effects of Ag and Ca to enhance the stability of G.P. zones are much stronger than these of Zr and Al, which is consistent with the experimental observation that Ag and Ca can promote efficiently the density of precipitation of G.P. zones in Mg-Zn alloys, but Zr and Al cannot. We also find that the combined addition of Ag and Ca not only enhances the stability of G.P. zones but also decreases the difference of formation energies of G.P. zones parallel to different habit planes, which provides conditions for increasing nucleation sites for G.P. zones that corresponds better strengthening effect. Furthermore, we analyze electronic structures to understand the different roles of these alloy elements in alteration of stability of G.P. zones.

The effect of Ag and Ca additions on the age hardening response of Mg–Zn alloys

The effect of sole and combined additions of Ag and Ca in enhancing the age hardening response in a Mg–2.4Zn (at%) alloy have been studied by systematic microstructure investigations using transmission electron microscopy (TEM) and three dimensional atom probe (3DAP). In the early aging stage of a Mg–2.4Zn–0.1Ag–0.1Ca (at%) alloy at 160°C, Zn-rich Guinier Preston (G.P.) zones form with Ag and Ca enrichment. Further aging lead to the formation of fine β′1 precipitates with Ag and Ca enrichment. We confirmed that the G.P. zones do not form in the Mg–2.4Zn (at%) binary alloy at 160°C, but form after a prolonged aging at 70°C. This suggests that the combined addition of Ag and Ca shifts the metastable solvus for the G.P. zones to a higher temperature, thereby making it possible to form G.P. zones even at the artificial aging temperature of 160°C. Since G.P. zones act as nucleation sites for the β′1 precipitates, the peak-aged microstructure is refined substantially by the addition of Ag and Ca.

Trace Element Effects on Microstructure and Mechanical Properties in Al-Cu-Li Alloy after Thermal Exposure

The effects of trace Ce, Ag on the microstructure and mechanical properties of Al-Cu-Li alloy after thermal exposure have been investigated. It’s found that the addition of Ce may lead to a slight increase in mechanical properties after thermal exposure at 107 . The stability of T1 phase is enhanced by independent Ag addition and the combined additions of Ag and Ce,which results in higher strength compared with Ag-free alloy at 150 thermal exposure. However, at 200 exposure, a great number of q¢ precipitates at the expense of T1 may be responsible for higher tensile strength in the Ag-free alloy than that of the independent addition of Ag and combined additions of Ag and Ce alloys.

Effects of trace silver and magnesium on the microstructure and mechanical properties of Al−Cu−Li alloys

The effects of trace silver and magnesium additions on the microstructure and mechanical properties of the Al−Cu−Li alloys were investigated. The experimental results indicate, that the effect of combined additions of Ag and Mg is the most obvious, the next is that of individual addition of Mg, and that of individual addition of Ag is the least. The addition of Ag and Mg in Al−Cu−Li alloy accelerates the precipitation of T1 and results in increasing the ageing hardness and strength. Prior cold work significantly improves the tensile strength by enhancing T1 precipitation in all the alloys investigated.

Classification of the role of microalloying elements in phase decomposition of Al based alloys

The fundamental role of microalloying elements in several aluminium alloys such as Al–Cu, Al–Li–Cu and Al–Cu–Mg has been investigated using a Monte Carlo computer simulation. All the utilized simulation parameters, e.g. pair interactions between same atoms species, between different atom species and between an atom and a vacancy, were derived from known thermodynamic or kinetic quantities. A small addition of Mg to Al–Cu alloys exhibits a strong tendency to form Mg/Cu/Vacancy complexes in the atom configurations, which is more remarkably revealed in Al–Li–Cu alloys. The combined addition of Ag or Si with Mg significantly increases the number of Mg/Cu/Vacancy complexes in Al–Cu–Mg alloys. From the comparison with experimentally reported results, these complexes are reasonably regarded as an effective heterogeneous nucleation site for GP zones, GPB zones and/or the Ω phase. The utilized simulation model, furthermore, permits the role of microalloying elements to be well classified in terms of the characteristic features of each element.

Compositional characterization of Cu-rich phase particles present in as-cast Al-Cu-Mg(-Li) alloys containing Ag

The effects of small additions of Ag on the aging of wrought Al-Cu-Mg(-Li) alloys, involving widespread nucleation of Cu-rich Ω (and T1) phase precipitates, are known. This article examines the influence of small additions of Ag on the nature of Cu-rich θ-Al2Cu, S-Al2CuMg, and T1-Al2CuLi phases present in appropriate as-cast Al-Cu, Al-Cu-Mg, and Al-Cu-Li-Mg alloys. Using a combination of light microscopy, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA), it is shown that neither independent nor combined additions of Ag and Mg to the binary Al-Cu alloy alter the composition of the θ phase; however, there are differences in the ways the θ phase is evolved in Al-Cu-Mg alloys with and without Ag. Ag additions to the Al-Cu-Mg alloy result in the formation of an Al-Cu-Mg-based ternary phase, having a Cu content similar to that of the θ phase and containing small amounts of Mg; rapid rates of cooling cause the retention of this phase in the as-cast alloy. Relatively large amounts of both Ag and Mg are always located in the peripheral regions of such a phase. This phase is readily replaced by θ phase upon annealing at 450 °C. The S phase of the ternary Al-Cu-Mg system is identified in this alloy and is found to dissolve small amounts of Ag. In the case of the Al-Cu-Li-Mg-Ag alloy, two major changes are observed: both Ag and Mg are always present in relatively large amounts in the peripheral regions of the T1 phase, and the S-phase particles are once again found to dissolve small amounts of Ag. These results are discussed in light of the known compositional features of the precipitates formed in the artificially aged Al-Cu-Mg(-Li)-Ag alloys, to reveal that examination of phases present in the as-cast microstructure is a contributory step toward determining the locations of trace alloy additions in the phase precipitates of interest.