• Journal of Korea Foundry Society
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• v.17 no.3
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• pp.245-251
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• 1997

Solderability, interfacial reaction and mechanical properties of joint between Sn-Bi-Ag base solder and Cu-substrate were studied. Solders were subjected to aging treatments to see the change of mechanical properties for up to 30 days at $100^{\circ}C$, and then also examined the changes of microstructure and morphology of interfacial compound. Sn-Bi-Ag base solder showed about double tensile strength comparing to Pb-Sn eutectic solder. Addition of 0.7wt%Al in the Sn-Bi-Ag alloy increase spread area on Cu substrate under R-flux and helps to reduce the growth of intermetallic compound during heat-treatment. According to the aging experiments of Cu/solder joint, interfacial intermetallic compound layer was exhibited a parabolic growth to aging time. The result of EDS, it is supposed that the soldered interfacial zone was composed of $Cu_6Sn_5$.

• Korean Journal of Materials Research
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• v.17 no.8
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• pp.420-424
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• 2007

Precipitation behavior has been studied in NiTi-based ordered alloy using transmission electron microscopy. The hardness after solution treatment is high in NiTi alloy suggesting the large contribution of solid solution strengthening in this alloy system. However, the amount of age hardening is not large as compared to the large microstructural variations during aging. At the beginning of aging, the $L2_1-type$ $Ni_2AlTi$ precipitates keep a lattice coherency with the NiTi matrix. By longer periods of aging $Ni_2AlTi$ precipitates lose their coherency and change their morphology to the globular ones surrounded by misfit dislocations. Misfit dislocations, which are observed on {100} planes of H-precipitates have the Burgers vector of a <100> with a pure edge type. The lattice misfits of $NiTi-Ni_2AlTi$ system is estimated from the spacings of misfit dislocations to be 1.3% at 1273 K. The lattice misfits decrease with increasing aging temperature in this system.

• Korean Journal of Materials Research
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• v.28 no.9
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• pp.495-498
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• 2018

Intermetallic compound matrix composites have been expected to be established as high temperature structural components. $Ni_3Al$ is a representative intermetallic alloy, which has excellent ductility even at room temperature by adding certain alloying elements. $Ni_3Al$ matrix composites with aluminum oxide particles, which are formed by the in-situ reaction between the alloy and aluminum borate whiskers, are fabricated by a powder metallurgical method. The addition of aluminum borate whiskers disperses the synthetic aluminum oxide particles during sintering and dramatically increases the strength of the composite. The uniform dispersion of reaction synthesized aluminum oxide particles and the uniform solution of boron in the matrix seem to play an important role in the improvement in strength. There is a dramatic increase in strength with the addition of the whisker, and the maximum value is obtained at a 10 vol% addition of whisker. The $Ni_3Al$ composite with 10 vol% aluminum oxide particles $0.3{\mu}m$ in size and with 0.1 wt% boron powder fabricated by the conventional powder metallurgical process does not have such high strength because of inhomogeneous distribution of aluminum oxide particles and of boron. The tensile strength of the $Ni_3Al$ with a 10 vol% aluminum borate whisker reaches more than twice the value, 930 MPa, of the parent alloy. No third phase is observed between the aluminum oxide and the matrix.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.51-57
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• 2007

The present work was aimed to examine the variation of microstructure and mechanical properties by annealing($100{\sim}620^{\circ}C$, $2{\sim}8hr$) in A3003 Al alloy welded pipes. The A3003 Al alloy pipes with 34 mm in external diameter and 1.3 mm in thickness were manufactured by high frequency induction welding with the V shaped convergence angle $6.7^{\circ}$ and power input 50 kW. The tensile and yield strength decreased with increasing the annealing temperature remarkably, but elongation increased remarkably. Vickers hardness in welds decreased with increasing the annealing temperature remarkably. The primary intermetallic compound of $Al_{12}(Fe,\;Mn)_2Si$ was precipitated in welds as the same base metal. In a certain experimental condition, the welds line in A3003 alloys disappeared at $450^{\circ}C$ for 2 hr because of the same mechanical property and structure between welds and base metal.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.112-116
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• 2015

This work studied the thickness and contact angle of solder joints between SAC 305 lead-free solder alloy and a Copper (Cu) substrate. Intermetallic compound (IMC) thickness and contact angle of 3Sn-Ag-0.5Cu (SAC 305) leadfree solder were measured using varying aging times, at a fixed temperature at 30℃. The thickness of IMC and contact angle depend on the aging time. IMC thickness increases as the aging increases. The contact angle gradually decreased from 39.49° to 27.59° as aging time increased from zero to 24 hours for big solder sample. Meanwhile, for small solder sample, the contact angle increased from 32.00° to 40.53° from zero to 24 hours. The IMC thickness sharply increased from 0.007 mm to 0.011 mm from zero to 24 hours aging time for big solder. In spite of that, for small solder the IMC thickness gradually increased from 0.009 mm to 0.017 mm. XRD analysis was used to confirm the intermetallic formation inside the sample. Cu₆Sn₅, Cu₃Sn, Ni₃Sn and Ni₃Sn₂ IMC layers were formed between the solder and the copper substrate. As the aging time increased, the strength of the solder joint mproved due to reduced contact angle.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.3
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• pp.152-158
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• 2016

The bonding characteristics of MLCCs (multi layer ceramic capacitor, C1608) lead-free solder (SAC305) joints were evaluated through thermal shock test ($-40^{\circ}C{\sim}125^{\circ}C$, total 1,800 cycle). After the test, IMCs( intermetallic compounds) growth and cracks were verified, also shear strengths were measured for degradation of solder joints. In addition, The thermal stress distributions at solder joints were analyzed to compare the solder joints changes before and after according to thermal shock test by FEA (finite elements analysis). We considered the effects of IMCs growth at solder joints. As results, the bonding characteristics degradation was occurred according to initial crack, crack propagations and thermal stress concentration at solder-IMCs interface, when the IMCs grown to solder inside.

• Corrosion Science and Technology
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• v.19 no.3
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• pp.115-121
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• 2020

In this study, erosion tests and erosion-corrosion tests of Al5083-H321 aluminum alloy were conducted at various flow rates in seawater. The erosion tests were conducted at a flow rate of 0 to 20 m/s, and erosion-corrosion tests were performed by potentiodynamic polarization method at the same flow rate. Characteristic evaluation after the erosion test was conducted by surface analysis. Characteristic evaluation after the erosion-corrosion test was performed by Tafel extrapolation and surface analysis. The results of the surface analysis after the erosion test showed that surface damage tended to increase as the flow rate increased. In particular, intermetallic particles were separated due to the breakdown of the oxide film at 10 m/s or more. In the erosion-corrosion test, the corrosion current density increased as the flow rate increased. Additionally, the surface analysis showed that surface damage occurred in a vortex shape and the width of the surface damage tended to increase as the flow rate increased. Moreover, damage at 0 m/s, proceeded in a depth direction due to the growth of pitting corrosion, and the damaged area tended to increase due to acceleration of the intermetallic particle loss by the fluid impact.

• Journal of the Korean institute of surface engineering
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• v.48 no.1
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• pp.11-22
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• 2015

Pd alloy hydrogen membranes for hydrogen purification and separation need thermal stability at high temperature for commercial applications. Intermetallic diffusion between the Pd alloy film and the porous metal support gives rise to serious problems in long-term stability of Pd alloy membranes. Ceramic barriers are widely used to prevent the intermetallic diffusion from the porous metal support. However, these layers result in poor adhesion at the interface between film and barrier because of the fundamentally poor chemical affinity and a large thermal stress. In this study, we developed Pd alloy membranes having a dense microstructure and saturated composition on modified metal supports by advanced DC magnetron sputtering and heat treatment for enhanced thermal stability. Experimental results showed that Pd-Cu and Pd-Ag alloy membranes had considerably enhanced long-term stability owing to stable, dense alloy film microstructure and saturated composition, effective diffusion barrier, and good adhesive interface layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.204-207
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• 2003

The flip chip bonding utilizing self-aligning characteristic of solder becomes mandatory to meet to tolerances for the optical device. In this paper, a parametric study of aging condition and pad size of sample was conducted. A TiW/Cu UBM structure was adopted and sample was aging treated to analyze the effect of intermetallic compound with time variation. After aging treatment, the tendency to decrease in shear strength was measured and the structure of the fine joint area was observed by using SEM, TEM and EDS. In result, the shear strength was decreased of about 20% in the $100{\mu}m$ sample at $170^{\circ}C$ aging compared with the maximum shear strength of same pad size sample. In the case of the $120^{\circ}C$ aging treatment, 17% of decrease in shear strength was measured at the $100{\mu}m$ pad size sample. Also, intremetallic compound of $Cu_6Sn_5$ and $Cu_3Sn$ were observed through the TEM measurement by using an FIB technique that is very useful to prepare TEM thin foil specimens from the solder joint interface.

• Journal of Powder Materials
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• v.7 no.3
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• pp.143-148
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• 2000

NiAl alloy powders were prepared by mechanical alloying method and bulk specimens were produced using hot isostatic pressing techniques. This study focused on the transformation behavior and properties of Ni-Al mechanically alloyed powders and bulk alloys. Transformation behavior was investigated by differential scanning calorimeter (DSC), XRD and TEM. Particle size distribution and microstructures of mechanically alloyed powders were studied by particle size analyzer and scanning electron microscope (SEM). After 10 hours milling, XRB peak broadening appeared at the alloyed powders with compositions of Ni-36at%Al to 40at%Al. The NiAl and $Ni_3Al$ intermetallic compounds were formed after water quenching of solution treated powders and bulk samples at $1200^{\circ}C$, but the martensite phase was observed after liquid nitrogen quenching of solution treated powders. However, the formation of $Ni_3Al$ intermetallic compounds were not restricted by fast quenching into liquid nitrogen. It is considered to be caused by fast diffusion of atoms for the formation of stable $\beta$(NiAl) phase and $Ni_3Al$ due to nano sized grains during quenching. Amounts of martensite phase increased as the composition of aluminium component decreased in the Ni-Al alloy, which resulted in the increasing damping properties.