Composite materials offer distinct and unique properties that are not naturally inherited in the individual materials that make them. One of the most attractive composites to manufacture is the aluminum alloy matrix composite, because it usually combines easiness of availability, light weight, strength, and other favorable properties. In the current work, Powder Metallurgy Method (PMM) is used to prepare Al2024 matrix composites reinforced with different mixing ratios of yttrium oxide (Y2O3) particles. The tests performed on the composites include physical, mechanical, and tribological, as well as microstructure analysis via optical microscope. The results show that the experimental density slightly decreases while the porosity increases when the reinforcement ratio increases within the selected range of 0 ~ 20 wt%. Besides this, the yield strength, tensile strength, and Vickers hardness increase up to a 10 wt% Y2O3 ratio, after which they decline. Moreover, the wear results show that the composite follows the same paradigm for strength and hardness. It is concluded that this composite is ideal for application when higher strength is required from aluminum composites, as well as lighter weight up to certain values of Y2O3 ratio.

In this study, we investigate the recycling of aluminum-based metal matrix composites(AMCs) embedded with SiC particulates. The microstructure of the AMCs is characterized by X-ray diffraction and scanning electron microscopy. The possibility of recycling the composite scrap is attempted from the melted alloy and SiC particulates by re-melting, holding and solidification in crucibles. The recovery percentage of the matrix alloy is calculated after a number of holding times, 0, 5, 10, 15, 20, 25 and 30 minutes and for different particulate sizes and weight fractions in the Al matrix. The results show that the recovery percentage of the matrix alloy, as well as the time required for maximum recovery of the matrix, is dependent on the size and weight fraction of SiC particulates. In addition, the percentage recovery increases with particulate size but drops with the particulate fraction in the matrix. The time to reach maximum recovery falls rapidly with an increase in particulate size and fraction.

A powder-in-sheath rolling method was applied to a fabrication of a carbon nano tube (CNT) reinforcedaluminum composite. A STS304 tube with an outer diameter of 34 mm and a wall thickness of 2 mm was used as asheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol was filled inthe tube by tap filling and then processed to 73.5% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the powder-in-sheath rolling decreased slightly with increasing of CNTs content, but exhib-ited high value more than 98. The grain size of the aluminum matrix was largely decreased with addition of CNTs; itdecreased from 24 µm to 0.9 µm by the addition of only 1 volCNT. The average hardness of the composites increasedby approximately 3 times with the addition of CNTs, comparing to that of unreinforced pure aluminum. It is concludedthat the powder-in-sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.

Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.

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.

SiC 보강재 표면에 도금된 Cu금속층이 Al/SiC복합재료의 젖음성에 미치는 영향을 검토하였다. 보강재에 대한 금속층의 도금은 무전해도금법을 이용하였으며, Al/SiC 복합재료의 제조는 텅스텐 발열체 진공로의 670˚C~900˚C에서 제조하여 보강재와 기지간의 접촉부위를 촬영하여 젖음성을 측정하였다 젖음성 측정 결과 보강재에 도금된 Cu층은 젖음성을 향상시켰고, 젖음성의 개선은 보강재에 도금된 금속층과 기지간의 반응에 의해 계면에너지를 변화시킴으로서 나타난 결과이며. 반응을 통한 산화피막의 배제도 영향을 미친 것으로 판단된다

금속기지 복합물은 구조용 재료로서 매우 우수한 성질을 지니고 있어 광범위하게 연구되어져 왔다. Al2O3와 SiC는 그들의 우수한 기계적 특성 때문에 일반적인 보강재로서 사용되어져 왔다. 그러나 이들 세라믹 보강재는 비싼 재조 비용 때문에 특별한 목적을 위해서만 한정되어 사용되어져 왔다. 본 연구에서는 우리는 Al 합금기지 복합물에서 SHS법에 의해 합성된 Al2O3-SiC 분말의 보강재로서의 응용 가능성을 살펴보았다. 또한 Al2O3단섬유를 Al기지 하이브리드 복합물에 적용하기 위하여 합성된 분말과 함께 첨가하였다. 25vol% 강화재의 복합물을 제조하기 위하여 용탕단조법을 사용하였다. 미세구조와 결정구조는 SEM, OM 그리고 XRD로 관찰하였고 압축시험과 마모시험으로 기계적인 성질들을 조사하였다.

Vacuum Hot Pressing을 이용하여 제조한 TiNi형상기억섬유 강화 6061 AI기지 복합재료를 제조하고 미세조직 및 기계적 특성 등을 연구하였다. 제조된 복합재의 항복응력은 예비변형량, 섬유체적율 및 열처리에 따라 증가하였다. 복합재의 지적특성은 예비변형이 가하여진 후 재가열되었을 때 기지 내 TiNi 섬유의 형상기억효과에 의한 압축잔류응력 발생에 기인된다. 미세조직 관찰 섬유와 기지 사이에는 AI3Ti및 AI3Ni의 금속간화합물층이 관찰되었다. 또한 시험온도 증가와 더불어 TiNi섬유강화된 복합재의 유동강도는 높은 값을 나타내었다.