In Situ Observation of Deformation in a Sn-3Ag-0.5Cu/Cu Solder Joint Using High-Voltage Transmission Electron Microscopy.

For reliable electronics, it is important to have an understanding of solder joint failure mechanisms. However, because of difficulties in real-time atomistic scale analysis during deformation, we still do not fully understand these mechanisms. Here, we report on the development of an innovative in situ method of observing the response of the microstructure to tensile strain at room temperature using high-voltage transmission electron microscopy (HV-TEM).

The Effect of In Concentration and Temperature on Dissolution and Precipitation in Sn-Bi Alloys.

Sn-Bi-based, low-temperature solder alloys are being developed to offer the electronics manufacturing industry a path to lower temperature processes. A critical challenge is the significant microstructural and lattice parameter changes that these alloys undergo at typical service temperatures, largely due to the variable solubility of Bi during the Sn phase. The influence of alloying additions in improving the performance of these alloys is the subject of much research.

Phase Transformations and Mechanical Properties in In-Bi-Sn Alloys as a Result of Low-Temperature Storage.

The In-Bi-Sn low-temperature solder alloys are regarded as potential candidates for cryogenic and space exploration applications. This study investigates the variations in the mechanical properties and microstructures of two different compositions: In15wt%Bi35wt%Sn and In30wt%Bi20wt%Sn, after exposure to a low-temperature environment (-20 °C) for 10 months. An increase in the ultimate tensile strength was observed across all the tested samples and a decrease in elongation to failure was observed in In30wt%Bi20wt%Sn.

Mechanical Properties and Microstructure of Binary In-Sn Alloys for Flexible Low Temperature Electronic Joints.

This research evaluates the mechanical properties of a variety of binary In-Sn alloys as potential candidates for low temperature electronic joints. The tensile and hardness tests of as-cast In-5Sn, In-12.5Sn, In-25Sn, In-30Sn, In-35Sn, In-40Sn, In-50Sn, In-60Sn, In-80Sn (wt.

In Situ Observation of Liquid Solder Alloys and Solid Substrate Reactions Using High-Voltage Transmission Electron Microscopy.

The complex reaction between liquid solder alloys and solid substrates has been studied ex-situ in a few studies, utilizing creative setups to "freeze" the reactions at different stages during the reflow soldering process. However, full understanding of the dynamics of the process is difficult due to the lack of direct observation at micro- and nano-meter resolutions. In this study, high voltage transmission electron microscopy (HV-TEM) is employed to observe the morphological changes that occur in CuSn between a Sn-3.

Effect of Na and Cooling Rate on the Activation of Mg-Ni Alloys for Hydrogen Storage.

In spite of favourable hydrogen storage properties such as low density, high theoretical capacity (7.6 wt% H/MgH₂) and economics, commercial use of Mg-based alloys is not feasible due to long activation times, slow hydrogen sorption kinetics, and a high temperature for hydrogen release. Mg- Ni alloys have been considered promising materials for hydrogen storage systems as the Mg₂Ni intermetallic phase enhances the kinetics of hydrogen absorption in Mg-Ni alloys through a catalytic effect.

The Effects of Trace Sb and Zn Additions on CuSn Lithium-Ion Battery Anodes.

Sn-based compounds are promising candidates for application as anodes in lithium-ion batteries (LIBs) due to the favourable storage capacity of Sn at 993 mAh g compared to carbon at 372 mAh g. The use of Sn-based anodes also avoids some of the safety concerns associated with carbon anodes. However, the large volume changes during lithiation and delithiation of pure Sn anodes often results in poor cyclic performance.

Imaging the Polymorphic Transformation in a Single Cu₆Sn₅ Grain in a Solder Joint.

In-situ observations of the polymorphic transformation in a single targeted Cu₆Sn₅ grain constrained between Sn-0.7 wt % Cu solder and Cu-Cu₃Sn phases and the associated structural evolution during a solid-state thermal cycle were achieved via a high-voltage transmission electron microscope (HV-TEM) technique. Here, we show that the monoclinic η'-Cu₆Sn₅ superlattice reflections appear in the hexagonal η-Cu₆Sn₅ diffraction pattern upon cooling to isothermal 140 °C from 210 °C.

(Al,Mg)La: a new phase in the Mg-Al-La system.

During an investigation of the Mg-rich end of the Mg-Al-La system, a new ternary phase with the composition of (Al,Mg)La was identified. The crystal structure of this phase was determined by conventional X-ray powder diffraction and transmission electron microscopy analysis and refined using high-resolution X-ray powder diffraction. The (Al,Mg)La phase is found to have an orthorhombic structure with a space group of C222 and lattice parameters of a = 4.

Reply to 'Comments on "Evidence of the hydrogen release mechanism in bulk MgH"'.

In a comment on our Article "Evidence of the hydrogen release mechanism in bulk MgH", Surrey et al. assert that the MgH sample we studied was not MgH at any time but rather MgO; and that the transformation we observed was the formation of Kirkendall voids due to the outward diffusion of Mg. We address these issues in this reply.

Evidence of the hydrogen release mechanism in bulk MgH2.

Hydrogen has the potential to power much of the modern world with only water as a by-product, but storing hydrogen safely and efficiently in solid form such as magnesium hydride remains a major obstacle. A significant challenge has been the difficulty of proving the hydriding/dehydriding mechanisms and, therefore, the mechanisms have long been the subject of debate. Here we use in situ ultra-high voltage transmission electron microscopy (TEM) to directly verify the mechanisms of the hydride decomposition of bulk MgH2 in Mg-Ni alloys.

Aluminium phosphide as a eutectic grain nucleus in hypoeutectic Al-Si alloys.

Aluminium phosphide (AlP) particles are often suggested to be the nucleation site for eutectic silicon in Al-Si alloys, since both the crystal structure and lattice parameter of AlP (crystal structure: cubic F43m; lattice parameter: 5.421 A) are close to that of silicon (cubic Fd3m, 5.431 A), and the melting point is higher than the Al-Si eutectic temperature.