Solidification of Eutectic Bi32.5In51Sn16.5 Alloy under Microgravity Using a Drop Tube

Containerless solidification of Bi32.5In51Sn16.5 eutectic alloy under microgravity conditions was investigated by using a 3 m length drop tube. The Bi-In-Sn system is an important material for lead-free solder and fuse element for electrical protection. It has a low eutectic melting temperature of 60°C, which is suitable for experiments in restricted environments like the International Space Station (ISS), where the security requirements are very strict. Droplets, with diameters in the range of 200 to 400 m, solidified under microgravity, were obtained consistently with irregular ternary eutectic structure, whereas, previous results under normal gravity presented both regular lamellar and irregular structures.

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Microstructural evolution in lead-free solder alloys: Part I. Cast Sn–Ag–Cu eutectic

Journal of Materials Research ◽

10.1557/jmr.2004.0190 ◽

2004 ◽

Vol 19 (5) ◽

pp. 1417-1424 ◽

Cited By ~ 66

Author(s):

Sarah L. Allen ◽

Michael R. Notis ◽

Richard R. Chromik ◽

Richard P. Vinci

Keyword(s):

Effective Activation Energy ◽

Ternary Eutectic ◽

Eutectic Structure ◽

Lead Free ◽

Lead Free Solder ◽

Solder Alloys ◽

Controlling Mechanism ◽

Coarsening Kinetics ◽

Free Solder

Coarsening of the ternary eutectic in cast Sn–Ag–Cu lead-free solder alloys was investigated. The process was found to follow r3 ∝ t kinetics where r is the rod radius of the dispersed phase and t is time. The effective activation energy for the process is 69 ± 5 kJmol-1. The two types of intermetallic rods, Cu6Sn5 and Ag3Sn, in the eutectic structure coarsen at different rates, with each having a different rate-controlling mechanism. The overall coarsening kinetics for the Sn–Ag–Cu ternary eutectic is significantly slower than that found for the Pb-Sn eutectic, which has implications for long-term reliability of Sn–Ag–Cu solder joints.

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Containerless Solidification of Eutectic PbSn Alloy Droplets in a Drop Tube

Materials Science Forum ◽

10.4028/www.scientific.net/msf.727-728.1633 ◽

2012 ◽

Vol 727-728 ◽

pp. 1633-1637 ◽

Cited By ~ 2

Author(s):

Rafael Cardoso Toledo ◽

F.E. de Freitas ◽

Chen Y. An ◽

I.N. Bandeira

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Energy Dispersive Spectrometry ◽

Lead Concentration ◽

Low Cost ◽

Microgravity Environment ◽

Drop Tube ◽

Irregular Structures ◽

Containerless Solidification ◽

Scanning Electron

Containerless solidification of 300 to 850 µm diameter droplets of PbSn eutectic alloy was achieved by using a 3m length drop tube, which is one of the most suitable and low cost option to provide a microgravity environment on the ground. Phase morphology and composition were investigated, respectively, by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). It was found that the microstructure of the droplets depends on their sizes, where in larger diameters (>500µm) consists of both regular lamellar and irregular structures, and on other hand, for the smaller ones (<500µm) the structure is only irregular with higher lead concentration.

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Antiprobcotron magnetic trap for charged dust particles in space experiments

Space engineering and technology ◽

10.33950/spacetech-2308-7625-2019-3-20-29 ◽

2019 ◽

pp. 20-29

Author(s):

Lev G. D’YACHKOV ◽

Mikhail M. VASILYEV ◽

Oleg F. PETROV ◽

Sergey F. SAVIN ◽

Igor V. CHURILO

Keyword(s):

Magnetic Trap ◽

Space Station ◽

Coulomb Systems ◽

Inhomogeneous Magnetic Field ◽

Dust Particles ◽

Charged Dust ◽

Magnetic Traps ◽

Space Experiments ◽

Microgravity Conditions ◽

New Space

We discuss the possibility of using static magnetic traps as an alternative to electrostatic traps for forming and confining structures of charged dust particles in a gas discharge plasma in the context of our study of strongly interacting Coulomb systems. Some advantages of confining structures in magnetic traps over electrostatic ones are shown. Also we provide a review of the related researches carried out first in laboratory conditions, and then under microgravity conditions including the motivation of performing the experiments aboard the International Space Station (ISS). The preparations of a new space experiment «Coulomb-magnet» as well as the differences of a new equipment from previously used are described. We proposed the main tasks of the new experiment as a study of the dynamics and structure of active monodisperse and polydisperse macroparticles in an inhomogeneous magnetic field under microgravity conditions, including phase transitions and the evolution of such systems in the kinetic heating of dust particles by laser radiation. Key words: Coulomb structures, magnetic trap, antiprobotron, diamagnetic particles, dust particles, microgravity.

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Thermophysical Properties of Fluids Measured Under Microgravity Conditions

MRS Proceedings ◽

10.1557/proc-551-171 ◽

1998 ◽

Vol 551 ◽

Author(s):

H.-J. Fecht ◽

R.K. Wunderlich

Keyword(s):

Thermophysical Property ◽

Thermophysical Properties ◽

European Space Agency ◽

Space Station ◽

Space Flights ◽

Space Agency ◽

Property Data ◽

Microgravity Conditions ◽

Key Industries ◽

Sufficient Precision

AbstractThe analysis of nucleation and growth processes relies mostly on circular arguments since basic thermophysical properties necessary, such as the Gibbs free energy (enthalpy of crystallization, specific heat), the density, emissivity, thermal conductivity (diffusivity), diffusion coefficients, surface tension, viscosity, interfacial crystal / liquid tension, etc. are generally unknown with sufficient precision and therefore often deduced from insufficient linear interpolations from the elements. The paucity of thermophysical property data for commercial materials as well as research materials is mostly a result of the experimental difficulties arising from the unwanted convection and reactions of melts with containers at high temperatures. An overview will be given on the results of thermophysical property measurements during several different space flights using containerless processing methods. Furthermore, a perspective on a future measurement program of thermophysical properties supported by the European Space Agency is described. In this regard, the International Space Station is considered as the ideal laboratory for high precision measurements of thermophysical properties of fluids which help to improve manufacturing processes for a number of key industries.

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Effects on the microstructure and mechanical properties of Sn-0.7Cu lead-free solder with the addition of a small amount of magnesium

Science and Engineering of Composite Materials ◽

10.1515/secm-2014-0130 ◽

2016 ◽

Vol 23 (6) ◽

pp. 641-647

Author(s):

Her-Yueh Huang ◽

Chung-Wei Yang ◽

Yu-Chang Peng

Keyword(s):

Mechanical Properties ◽

Aging Process ◽

Intermetallic Layer ◽

Eutectic Structure ◽

Contact Angles ◽

Solidification Structure ◽

Lead Free Solder ◽

Bulk Alloy ◽

Scanning Calorimetry ◽

Free Solder

AbstractThe influence of a small amount of magnesium (only 0.01 wt.%) added to the Sn-0.7Cu solder alloy during the aging process of microstructural evolution is studied along with the mechanical properties of the alloy. The experimental results indicate that the addition of magnesium decreases the tensile strength of the solders but improves their elongation. The solidification structure of eutectic Sn-0.7Cu consists of β-Sn, and the eutectic structure, which has extremely fine intermetallic nodules, Cu6Sn5, is located in the interdendritic region. When the magnesium is added to the Sn-0.7Cu alloy, the Sn dendrites become slightly coarser; in comparison, the melting point of the Sn-0.7Cu-0.01Mg alloy decreased by 2°C for the differential scanning calorimetry results of bulk alloy samples. Sn-0.7Cu-0.01Mg exhibits the lowest contact angles and the widest spreading areas. After aging, the Sn-0.7Cu and Sn-0.7Cu-0.01Mg solders show significant changes in strength, mainly because of the obvious increase in the thickness of the Cu6Sn5 intermetallic layer.

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Improved resolution crystal structure of Acanthamoeba actophorin reveals structural plasticity not induced by microgravity

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x21011419 ◽

2021 ◽

Vol 77 (12) ◽

Author(s):

Stephen Quirk ◽

Raquel L. Lieberman

Keyword(s):

Crystal Structure ◽

Conformational Changes ◽

Actin Filaments ◽

Space Station ◽

Acanthamoeba Castellanii ◽

Test Case ◽

Molecular Replacement ◽

International Space ◽

Microgravity Conditions ◽

Turn Region

Actophorin, a protein that severs actin filaments isolated from the amoeba Acanthamoeba castellanii, was employed as a test case for crystallization under microgravity. Crystals of purified actophorin were grown under microgravity conditions aboard the International Space Station (ISS) utilizing an interactive crystallization setup between the ISS crew and ground-based experimenters. Crystals grew in conditions similar to those grown on earth. The structure was solved by molecular replacement at a resolution of 1.65 Å. Surprisingly, the structure reveals conformational changes in a remote β-turn region that were previously associated with actophorin phosphorylated at the terminal residue Ser1. Although crystallization under microgravity did not yield a higher resolution than crystals grown under typical laboratory conditions, the conformation of actophorin obtained from solving the structure suggests greater flexibility in the actophorin β-turn than previously appreciated and may be beneficial for the binding of actophorin to actin filaments.

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Dendritic Growth of Rapid-Solidified Eutectic High-Entropy Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1035.46 ◽

2021 ◽

Vol 1035 ◽

pp. 46-50

Author(s):

Lei Gang Cao ◽

Peng Yu Hou ◽

Ahmed Nassar ◽

Andrew M. Mullis

Keyword(s):

Cooling Rate ◽

Single Phase ◽

Eutectic Growth ◽

Sample Surface ◽

Eutectic Structure ◽

High Entropy Alloy ◽

Drop Tube ◽

Dendrite Morphology ◽

High Entropy ◽

Mould Casting

Mould casting and drop-tube techniques were used to solidify a AlCoCrFeNi2.1 eutectic high-entropy alloy under conditions of high cooling rate. The samples obtained from two different methods present the same phase constituent, FCC and B2 phases. During mould casting experiments the alloy almost solidified into the eutectic structure consisting of lamellar and anomalous morphology, with a tiny fraction of cellular and dendrite morphology being observed at certain sites of the sample surface due to the corresponding high cooling rate. Instead, during drop-tube experiments a typical, coarse dendrite structure of FCC single phase was formed across the entire 106-150 μm particle. The cellular structure can also be formed directly from the melt. The rest region solidified into the general eutectic morphology as was observed in the casting rods. The results clearly indicate the transition from coupled eutectic growth to single-phase dendrite growth with increasing departures from equilibrium for the multi-component AlCoCrFeNi2.1 eutectic high-entropy alloy.

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Nanopore sequencing at Mars, Europa, and microgravity conditions

npj Microgravity ◽

10.1038/s41526-020-00113-9 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Christopher E. Carr ◽

Noelle C. Bryan ◽

Kendall N. Saboda ◽

Srinivasa A. Bhattaru ◽

Gary Ruvkun ◽

...

Keyword(s):

Parabolic Flight ◽

Space Station ◽

Space Vehicles ◽

Nanopore Sequencing ◽

Icy Moons ◽

Microbial Monitoring ◽

Oxford Nanopore ◽

Microgravity Conditions ◽

Low Mass ◽

Consistent Performance

Abstract Nanopore sequencing, as represented by Oxford Nanopore Technologies’ MinION, is a promising technology for in situ life detection and for microbial monitoring including in support of human space exploration, due to its small size, low mass (~100 g) and low power (~1 W). Now ubiquitous on Earth and previously demonstrated on the International Space Station (ISS), nanopore sequencing involves translocation of DNA through a biological nanopore on timescales of milliseconds per base. Nanopore sequencing is now being done in both controlled lab settings as well as in diverse environments that include ground, air, and space vehicles. Future space missions may also utilize nanopore sequencing in reduced gravity environments, such as in the search for life on Mars (Earth-relative gravito-inertial acceleration (GIA) g = 0.378), or at icy moons such as Europa (g = 0.134) or Enceladus (g = 0.012). We confirm the ability to sequence at Mars as well as near Europa or Lunar (g = 0.166) and lower g levels, demonstrate the functionality of updated chemistry and sequencing protocols under parabolic flight, and reveal consistent performance across g level, during dynamic accelerations, and despite vibrations with significant power at translocation-relevant frequencies. Our work strengthens the use case for nanopore sequencing in dynamic environments on Earth and in space, including as part of the search for nucleic-acid based life beyond Earth.

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