• Journal of Power System Engineering
• /
• v.21 no.2
• /
• pp.14-19
• /
• 2017

The corrosion characteristics of Al-Si-Mg alloy were investigated in $O_2$ and $H_2S/H_2$ environments at high temperature. The weight gain and the reaction rate constant of the Al-Si-Mg alloy were measured in the oxygen and hydrogen sulfide environments at 773K. The weight gain of Al-Si-Mg alloy was showed parabolic increase in the oxygen and hydrogen sulfide environments. The reaction rate constants were confirmed to be $1.45{\times}10^{-4}mg^2cm^{-4}sec^{-2}$ in the oxygen environment and $6.19{\times}10^{-4}mg^2cm^{-4}sec^{-2}$ in the hydrogen sulfide environment respectively. As a result of XPS analysis on the specimen surface, $Al_2O_3$ and MgO compounds were detected in oxygen environment and $Al_2(SO_4)_3$ sulfate was detected in the hydrogen sulfide environment. Corrosion rate of Al-Si-Mg alloy was about 4.3 times faster in hydrogen sulfide environment than oxygen environment.

• Journal of Korea Foundry Society
• /
• v.22 no.5
• /
• pp.257-264
• /
• 2002

Effects of Ca content on the refinement of primary Si of Aluminum B390 alloy have been examined. Ca was found to have an effect on the refinement of primary Si particle. Primary Si particle size has been refined as Ca content of the melts decreased and cooling rate increased. A control of Ca content by the addition of $CuCl_2$ to the melt was the most efficient in the refinement of primary Si particles. The minimum size of primary Si particles in this study was $15.0\;{\mu}m$ when a residual content of Ca element in the alloy was 5ppm, Primary Si particle size was refined as primary Si crystallization temperature increased, which was attributed to the decrease of Ca content in the melts.

• Journal of the Korean Society for Heat Treatment
• /
• v.33 no.5
• /
• pp.226-231
• /
• 2020

The Cu-Co-Si alloy shows high strength by forming precipitates by aging precipitation heat treatment of supersaturated solid solution treated with solution treatment such as Cu-Ni-Si alloy, and the Co₂Si precipitated phase is dispersed in the copper matrix. The effect of aging treatment on the microstructure, mechanical and electrical properties of Cu-Co-Si alloys for electronic devices was investigated. As a results of SEM/EDS analysis, it was found that Co₂Si precipitates of 30~300 nm size were distributed in grains. By performing the double aging treatment, it was possible to improve the strength and electrical conductivity by dispersing the fine precipitate evenly.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.12
• /
• pp.48-54
• /
• 2003

Alumium alloys casting are gaining increased acceptance in the automotive and electronic industeries and squeeze casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Al-7.0Si-0.4Mg (AC4C) alloy fabricated by squeeze casting process for development of Fuel system Parts (Fuel rail). The microstructure of squeeze casted specimen were composed of eutectic structure Alumimim solid solution and $Mg_2$Si precipitates. The tensile strength of as-solid solution treatment Al-7.0Si-0.4Mg ahoy revealed 298.5MPa. It was found that Al-7.0Si-0.4Mg alloy have good corrosion resistance in electrochemical polarization test.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.6
• /
• pp.20-26
• /
• 1995

With the recent development of light and high efficient automobiles and aircraft, demand of the A1-Si alloy is rapidly increasing. However, there is an inclination that as the content of silicon increases it becomes more difficult to machine. Accordingly, the present study intends to analyse and study the cutting resistance and surface roughness of A1-Si alloy with Si contents of 8%, 12%, 17%, and 20%. The A1-Si alloy specimens were turned by a poly- crystalline diamond tool under selected cutting conditions, and results are here described and discussed.

• Journal of Korea Foundry Society
• /
• v.29 no.1
• /
• pp.27-32
• /
• 2009

The microstructure of Al-7Si-0.4Mg-1Fe alloy mainly consists of aluminum dendrites, Al-Si eutectics, and $Al_5FeSi$ needles. When Mn was added to the alloy, the substantial amount of $Al_5FeSi$ phase was changed into Al(Mn,Fe)Si, however the needle-like morphology was almost unchanged. Combined additions of Cr or Sr with Mn to the base alloy resulted in rod-like Al(Mn, Fe,Si)Si phase. The tensile properties of as-cast alloys were enhanced by the Mn addition, especially when it was added with Sr. The tensile properties after T6 heat treatment was a little improved with 0.7%Mn addition, but Cr or Sr additions with Mn didn't show any positive effect on the properties of heat-treated alloys.

• Korean Journal of Materials Research
• /
• v.31 no.11
• /
• pp.642-648
• /
• 2021

The precipitation effect of Al-6%Si-0.4%Mg-0.9%Cu-(Ti) alloy (in wt.%) after various heat treatments was studied using a laser flash device (LFA) and differential scanning calorimetry (DSC). Solid solution treatment was performed at 535 ℃ for 6 h, followed by water cooling, and samples were artificially aged in air at 180 ℃ and 220 ℃ for 5 h. The titanium-free alloy Al-6%Si-0.4%Mg-0.9%Cu showed higher thermal diffusivity than did the Al-6%Si-0.4%Mg-0.9%Cu-0.2%Ti alloy over the entire temperature range. In the temperature ranges below 200 ℃ and above 300 ℃, the value of thermal diffusivity decreased with increasing temperature. As the sample temperature increased between 200 ℃ and 400 ℃, phase precipitation occurred. From the results of DSC analysis, the temperature dependence of the change in thermal diffusivity in the temperature range between 200 ℃ and 400 ℃ was strongly influenced by the precipitation of θ'-Al₂Cu, β'-Mg₂Si, and Si phases. The most important factor in the temperature dependence of thermal diffusivity was Si precipitation.

• Journal of Powder Materials
• /
• v.23 no.5
• /
• pp.397-401
• /
• 2016

A lean alloy is defined as a low alloy steel with a minimum amount of the alloying element that maintains the characteristics of the sintered alloy. It is well known that the addition of elements such as Cr, P, Si, or Mn improves the mechanical characteristics of the alloy, but decreases the sinterability. The mother alloy is used to avoid an oxidation reaction with the alloying elements of Cr, P, Si or Mn. The purpose of this study is to determine the change in the mechanical properties of Fe-P-Mo and Fe-P-Mn alloys as a result of the addition of Si. In this article, the Fe-P-Mo and Fe-P-Mn alloys to which Si is added are compacted at $7.0g/cm^3$ and then sintered in $H_2-N_2$ at $1120^{\circ}C$. The P around the macropores and large grains reduces due to the formation of $SiO_2$ as the Si content increases. This is caused by the increase in strength owing to reducing intergranular fracture by suppressing the reaction with oxygen.

• Journal of the Korean Magnetics Society
• /
• v.10 no.6
• /
• pp.269-273
• /
• 2000

Fe-l7Cr-2M(M=Si, Nb, Mo) alloy powder was prepared by plasma electrode rotating atomizer and than the alloy powder was formed and sintered. The particle shape of the Fe-l7Cr-2M(M=Si, Nb, Mo) alloy power is spherical. The saturation magnetization of the sintered Fe-17Cr-2Mo and Fe-l7Cr-2Nb alloy are 155 emu/g. The saturation magnetization of the sintered Fe-l7Cr-2Si alloy is less than that of the sintered Fe-l7Cr-2Mo and Fe-l7Cr-2Nb alloy. The amplitude relative permeability of the sintered Fe-l7Cr-2M(M=Si, Nb, Mo) alloy has the maximum value in the range of 3∼5 Oe applied field at forming pressure 12 ton/cm$^2$, sintering temperature 1200$^{\circ}C$, and frequency 1 kHz. Power loss of the sintered Fe-l7Cr-2Nb alloy is 40 mW/cc at applied field, H$\sub$a/=5 Oe, and frequency, f=1 kHz. The power loss of the sintered Fe-l7Cr-2Nb alloy is a half of that of the sintered Fe-l7Cr-2Si and Fe-l7Cr-2Mo alloy.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.05a
• /
• pp.97-100
• /
• 2002

In this research, the impact behavior of the boundary between MMC-reinforced SiC whisker and Al alloy were studied. It is known that the resultant of the interfacial reaction between SiC whisker and Al alloy has brittle and low toughness property. In this paper, impact behavior of graded MMC & Al alloy shows the interfacial opening at the boundary. Generally this phenomenon is generated by thermal residual stress, brittle interfacial reaction resultant and difference of the deflection. So, these results may be interpreted as a macroscopic method of measuring the interfacial strength between matrix and reinforcement