The microstructural and mechanical properties of Al-Si alloyed powder, prepared by gas atomization fallowed by hot extrusion, were studied by optical and scanning electron microscopies, hardness and wear testing. The gas atomized Al-Si alloy powder exhibited uniformly dispersed Si particles with particle size ranging from 5 to . The hot extruded Al-Si alloy shows the average Si particle size of less than . After heat-treatment, the average particle size was increased from 2 to . Also, mechanical properties of extruded Al-Si alloy powder were analyzed before and after heat-treatment. As expected from the microstructural analysis, the heat-treated samples resulted in a decrease in the hardness and wear resistance due to Si particle growth. The friction coefficient of heat-treated Al-Si alloyed powder showed higher value tough all sliding speed. This behavior would be due to abrasive wear mechanism. As sliding speed increases, friction coefficient and depth and width of wear track increase. No significant changes occurred in the wear track shape with increased sliding speed.

The binder phase for TiC reinforced steel matrix composite was added in the form of elemental powders and master alloy powders. The microstructures, binder phase variation with TiC content and mechanical properties were evaluated. The addition of a type of binder phase largely effects the microstructure and mechanical properties. The binder phase variation from starting composition was observed with increase in wt% TiC content and this variation was higher when the master alloy powders were used as a binder. The response to heat treatment was decreased with an increase in TiC content due to the shift of binder phase from the starting composition.

The mixed atomized iron powders with 0.3% graphite and 1% Ni powders were cold pressed and sintered at for 30 min under pure Ar gas atmosphere. Some of the sintered specimens were intercritically annealed at and quenched in water (single quenching). The other sintered specimens were first fully austenized at and water quenched. These specimens were then intercritically annealed at and re-quenched in water. The experimental results showed that the wear coefficient effectively decreased in the double quenched specimen.

The characteristics of residual stresses occurring in PM steel based nickel (FLN2-4405) was investigated. The measurements of residual stresses were carried out by electrochemical layer removal technique. The values and distributions of residual stresses occurring in PM steel processed under various densities and heat treatment conditions were determined. In most of the experiments, tensile residual stresses were recorded in surface of samples. The residual stress distribution on the surface of the PM steels is affected by the heat treatment conditions and density. Maximum values of residual stresses on the surface were observed sinter hardened condition and density. Minimum level of recorded tensile residual stresses are150 MPa and its maximum level is 370 MPa.

The study examines hardness pattern of SH737-2Cu-.9C samples transient liquid phase sintered at different temperatures viz. , and , heat treated by various methods and then tempered at different temperatures. Sintered samples were characterized for density and densification parameter, and austenitized at , subsequently cooled by four different methods viz. annealing, normalizing, oil and brine quenching. Hardness pattern was found minimum for air cooled and maximum for brine quenched, and samples sintered at had relatively higher hardness. The O.Q and B.Q samples were then tempered at , , and . Hardness pattern typically showed secondary hardness taking place, with maximum around .

The corrosion performance of a powder metallurgical aluminum alloy in aeronautical environments was studied for both as sintered and heat treated states. Sintered samples were obtained by uniaxial pressing of an Al-Cu-Mg prealloyed powder followed by liquid phase sintering. The heat treatments applied were T4 and T6. Corrosion behaviour was assessed by means of potentiodynamic polarization. Results for the equivalent commercial wrought counterpart, AA2024-T3, are also presented for comparison. Similar corrosion performance was observed for both as sintered and AA2024-T3 samples, while corrosion resistance of the PM materials was improved by the heat treatment, especially in the T4 state.

is an extremely high alloyed PM material containing about 20 to 35 wt.% titanium based carbides. Such materials are designed to achieve a high wear resistance, but the high volume fraction of hard phases causes a comparable low ductility in case of tensile loading. In the present study the mechanical properties of different Ferro-Titanit grades (variations in chemical composition and in heat treatment) were investigated by means of tensile tests. The mechanical properties and the fracture behaviour will be related to the chemical composition, the heat treatment and the microstructure.

저장전 고온처리(38˚, 48시간)는 참외의 당도, 산도, 비타민 C의 함량과 α-tocopherol 활성을 높였으며, 3℃의 MA저장중 생체중 감소 이산화탄소, 에틸렌그리고 아세트알데히드 발생량을 낮게 유지시켰다. 또한 저장후 외관상 품질, 경도, 당도, 산도, 비타민 C, α-tocopherol 활성 등 내적품질이 고온처리한 참외에서 높은 수준을 유지하였는데 특히 저온장해정도를 알 수 있는 이온용 출량이 고온처리구에서 낮아 수확후 고온처리로 저온장해가 완화되었음을 알 수 있었다. 고온처리를 하지 않은 대조구는 저장 25일부터 Alternaria rot이 발견되었으나 고온처리구는 저장 종료일인 39일까지 부패가 발견되지 않았으며 외관상 품질에 대한 저장일수로 세운 회귀식에 의하면 저장수명이 고온처리구에서 8일 이상 연장되었다. 참외의 경우 저장전 38℃의 낮은 고온에서 장시간 열처리를 함으로써 살균효과 저온장해 완화효과와 더불어 수명연장까지 얻을 수 있었다.

The effect of post-heat treatment on the coating characteristics and the fatigue strength of the gas flame thermally sprayed Stellite alloy coatings on carbon steel were investigated. The fatigue fracture surfaces of the heat treated samples were observed using SEM (Scanning Electron Microscopy). For as-sprayed samples, there was considerable scattering in the fatigue life due to the presence of the pores in the coating. After the post-heat treatment to improve the microstructural characteristics of the coating layer, the fatigue strength of the specimens was greatly improved, increasing with increasing the coating thickness. For the specimens with the 0.3mm and 0.5mm thick coating, the fatigue cracks originated in the substrate region just below the interface. On the contrary, for the specimens with the 1.0mm thick coating, they nucleated at the pore within the coating, and the fatigue strength was 2.6 times higher than that of the substrate due to the high fatigue resistance of the coating.

Four different mechanical alloying(MA) processes were employed to fabricate very fine intermetallic compound particles dispersed Al composite materials(MMC) with Al-4at.%Zr composition. Phase transformations including phase stability during MA and heat treatment processes were investigated. Part of Zr atoms were dissolved into Al matrix and part of them reacted with hydrogen produced by decomposition of PCA(methanol) to form hydride during first MA process. These hydrides disappeared when alloy powders were heat treated at . Stable dispersoids with structure were formed by heat treating the mechanically alloyed powders at . On the other hand, metastable dispersoids with structure were formed during first MA of powers with Al-25at.%Zr composition. These metastable dispersoids transformed to stable with structure when heat treated above .