• Journal of Korea Foundry Society
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• v.10 no.1
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• pp.43-49
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• 1990

The influences of Cu and Mg addition on wear properties of SiC particulate reinforced Al-Si metal(alloy) matrix composites were investigated. Metal matrix composites were prepared by combination of compocasting and hot pressing techniques. The main results obtained are as follows : 1) The composite with Mg addition exhibits letter wear resistance than that with Cu addition. It is considered that Mg addition improved wettability of matal matrix composite by the strong segregation to the SiC / Al matrix interface. 2) After homogenization treatment, it was found that the interfacial segregation of Mg was predominant, while that of Cu was not detected. 3) The SiC / Al-11Si eutectic composite exhibits better wear resistance than the SiC / Al-6Si hypoeutectic composite does. 4) It seems that the increase in the amount of Mg addition affects on the uniform dispersion of SiC particulates, on the refinement of microstructure and on age hardening and these effects cause wear resistance improvement of composites.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1271-1272
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• 2006

The vacuum infiltration method is one of the composite producing methods. There are several parameters in composite production by vacuum infiltration. One of them is particle size of reinforcement in particulate reinforced composites. In this study, MgO powder and Al were used as reinforcement and matrix respectively. MgO powders with different size and amount to give same height were filled in quartz tubes and liquid metal was vacuum infiltrated into the MgO powder under same vacuum condition and for same time. Infiltration height was measured and microstructure and fracture behavior of composite were investigated. It has been found that infiltration height and fracture strength were increased with particulate reinforcement sizes. It has also been determined that molten metal temperature facilitates infiltration.

• Composites Research
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• v.33 no.5
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• pp.256-261
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• 2020

In this study, the ignition temperature of the Al-Ti-C reaction system, the microstructure and the mechanical properties of the TiC/Mg composite which produced by the self-propagating high-temperature synthesis (SHS) followed by stir casting process were investigated. Mg based composite with uniformly dispersed 0, 10, 20, and 30 vol.% TiC were fabricated, and higher volume fraction of TiC reinforced composite showed superior compressive strength and wear resistance as compared with Mg matrix. It is attributed to the less contamination, defects, impurities in TiC/Mg composite by the in-situ SHS yield effective load transfer from the matrix to the reinforcement.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.109-115
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• 2000

In the present study, (10%$Al_2O_3$+5%Si)/AZ91 Mg hybrid composite was fabricated using the squeeze casting method. During squeeze casting, molten Mg was infiltrated into the preform of 10%$Al_2O_3$+5%Si and reaction product of $Mg_2Si$ intermetallic compound was formed by the reaction between molten Mg and Si powder. Microstructure has been observed and mechanical properties were evaluated for the reaction squeeze cast (RSC) hybrid composite. It was found that Si powder totally reacted with molten Mg to form $Mg_2Si$. Reinforcement ($Al_2O_3$) and the reaction product ($Mg_2Si$) are fairly uniformly distributed in Mg matrix for the squeeze cast hybrid composite. Mechanical properties were improved with hybridization of reinforcements, namely higher hardness and enhanced wear resistance comparing squeeze cast (15%$Al_2O_3$)/AZ91 Mg composite.

• Journal of Korea Foundry Society
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• v.25 no.2
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• pp.80-87
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• 2005

The microstructure and mechanical property of the Ni and Ni-Cr porous metal reinforced AC4C matrix composites fabricated by squeeze casting were investigated. In this study Ni, Ni-Cr porous metals which are estimated to be easy to fabricate by squeeze casting are used as strengtheners for composite materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Ni/AC4C and Ni-Cr/AC4C composite, $750^{\circ}C$ melt temperature and minimum 25MPa squeezing pressure are needed to produce sound composite materials. The observation of interfacial reaction zone at various heat treatment condition shows that atsolutionizing temperature of above $520^{\circ}C$, the interfacial reaction zone increases proportionally with heat treatment time and the reaction products formed by interfacial reactions are mainly composed by $Al_{3}Ni$ and $Al_{3}Ni_{2}$ phases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.187-191
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• 2000

High temperature creep behaviour of Al-5 wt% Mg alloy reinforced with 7.5% BN flakes was studied. The composite specimens showed two main creep characteristics : (1) the value of the apparent stress exponent of the composite was high and varied with applied stress (2) the apparent activation energy for creep was much larger than that for self-diffusion in aluminum The true stress exponent of the composite was set equal to 5. Temperature dependence of the threshold stress of the composite was very strong. Which could not be rationalized by allowing for the temperature dependence of the elastic modulus change. AIN particles which were incorporated into the Al matrix during fabrication of the composite by the PRIMEXTM method were found to be effective barriers to dislocation motion and to give rise the threshold stress during creep of the composite

• Journal of Korea Foundry Society
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• v.29 no.4
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• pp.176-180
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• 2009

Effect of matrix microstructure on creep behaviors of squeeze cast magnesium matrix composites was investigated. Aluminum borate whisker was used as reinforcement and AZ31, AS52 and Sr added AS52 Mg alloys were used for matrix alloys. The reinforcement was distributed homogeneously and defect-free composite was manufactured. Creep tests were carried out at the temperature of $150^{\circ}C$ under the applied stress of 50 and 100 MPa for Mg alloys and Mg MMCs, respectively. The creep resistance of Mg MMCs was in this order: AS52-Sr > AS52 AZ31 MMCs. Void initiation during creep mainly occurred at $Mg/Mg_{17}Al_{12}$ interface and propagation went along grain boundaries. On the other hand, $Mg_2Si$ phase was not attributed to the creep void initiation.

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.791-795
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• 2005

In this study, aluminum borate whisker reinforced Mg-3Al-2Ag-1Zn matrix composites were fabricated by the squeeze infiltration technique. The purpose is to develop materials for elevated temperature applications. Microstructure observation revealed successful fabrication of the metal matrix composites, namely no cast defects such as porosity and matrix/reinforcement interface delamination etc. High temperature hardness and creep rupture properties were improved significantly with addition of Ag to the Al borate whisker reinforced Mg alloy composite. $Mg_3Ag$ phase formed during aging heat treatment could improve creep properties of the Mg matrix composites.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.139-142
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• 2000

The SiCp/AC8A composites were fabricated by the pressureless metal infiltration process successfully. The effect of additional Mg, which were mixed with SiC particles to promote interfacial wetting between the reinforcement and matrix alloy, and particle size on the mechanical properties was investigated. By increasing the additional Mg content the hardness of SiCp/AC8A composites was increased due to the hard reaction products, but the bending strength was decreased by the excess reaction of Mg and high porosity level when the additional Mg content is over 7%. The Hardness and bending strength was increased by decreasing the size of SiC particle.

• Journal of Korea Foundry Society
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• v.20 no.1
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• pp.13-20
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• 2000

In the present study,($10%Al_2O_3+5%Si$)/AZ91 Mg hybrid composite was fabricated using the squeeze casting method. During squeeze casting, Molten Mg was infiltrated into the preform of $10%Al_2O_3+5%Si$ and reaction product of $Mg_2Si$ intermetallic compound was formed by the reaction between molten Mg and Si Powder. Microstructure has been observed and mechanical properties were evaluated for the reaction squeeze cast(RSC) hybrid composite. It was found that Si powder totally reacted with molten Mg to form $Mg_2Si$. Reinforcement($Al_2O_3$) and the reaction product ($Mg_2Si$) are fairly uniformly distributed in Mg Matrix for the squeeze cast hybrid composite. Mechanical Properties were improved with hybridization of reinforcements, namely higher hardness and enhanced wear resistance comparing squeeze cast($15%Al_2O_3$)/AZ91 Mg composite.