• Journal of Powder Materials
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• v.10 no.1
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• pp.40-45
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• 2003

Sintering behavior of 2xxx series Al alloy was investigated to obtain full densification and sound microstructure. The commercial 2xxx series Al alloy powder. AMB2712, was used as a starting powder. The mixing powder was characterized by using particle size analyzer, SEM and XRD. The optimum compacting pressure was 200 MPa, which was the starting point of the "homogeneous deformation" stage. The powder compacts were sintered at $550~630^{\circ}C$ after burn-off process at $400^{\circ}C$. Swelling phenomenon caused by transient liquid phase sintering was observed below $590^{\circ}C$ of sintering temperature. At $610^{\circ}C$, sintering density was increased by effect of remained liquid phase. Further densification was not observed above $610^{\circ}C$. Therefore, it was determined that the optimum sintering temperature of AMB2712 powder was $610^{\circ}C$.}C$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1266-1267
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• 2006

[ $MgZn_{4.3}Y_{0.7}$ ] alloy powders were prepared using an industrial scale gas atomizer, followed by warm extrusion. The powders were almost spherical in shape. The microstructure of powders as atomized and bars as extruded was examined as a function of initial powder size distribution using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscope (EDS) and X-ray Diffractometer (XRD). The grain sizes were decreased with extruding as well as decreasing the initial powder sizes. Both the ultimate strength and elongation were enhanced as the initial powder sizes were decreased.

• Journal of Powder Materials
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• v.19 no.1
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• pp.67-71
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• 2012

The present paper gives an overview about the Atom Probe Tomography technique and its application to powder materials. The preparation of needle-shaped Atom Probe specimens from a single powder particle using focused-ion-beam milling is described. Selected experimental data on mechanically alloyed (and sintered) powder materials are presented, giving insight into the atomic-scale elemental redistribution occurring under powder metallurgical processing.

• Journal of Welding and Joining
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• v.13 no.1
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• pp.103-114
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• 1995

Plasma Transferred arc(PTA) hard facing process has been developed to obtain an overlay weld metal having excellent wear resistance. The effect of Ti, TiSi$_{2}$ and TiC powders addition on the surface of Aluminum alloy 5083 has been investigated with PTA process. This paper describes the result of test the performance of the overlay weld metal. The result can be summarized as follows 1. Intermetallic compound is formed on surface of base metal in Ti or TiSi$_{2}$ powder but the reaction with surface of base metal is little seen in TiC powder. 2. In formation of composite layer on aluminum alloy surface by plasma transferred arc welding process, high melting ceramics like TiC powder is excellent. 3. The multipass welding process is available for formation of high density of powder. But the more number of pass, the less effect of powder, it is considered, and limits of number of pass. 4. By increasing area fraction of TiC powder on Al alloy surface, in especially TiC powder the hardness increase more than 40% area fraction and 88% shows about Hv 700.

• Journal of Powder Materials
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• v.5 no.4
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• pp.319-323
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• 1998

Powder forging with a back pressure was investigated for production of automobile and compressor parts made of a rapidly solidified Al-Si alloy powder. Disk-shaped green compacts made of a rapidly solidified Al-Si alloy powder were hot forged, and hubs were formed by loading back pressure on their top. The influences of the back pressure and die temperatures on forgeabiliy and properties of parts made of a rapidly solidified Al-Si alloy powder were examined. This method was also applied to the production of a scroll part. The results of these studies are summarized as follows : 1. A back pressure on the hub top is very effective for consolidation and preventing crack formation in the hub. 2. When a back pressure tess than 98 MPa is applied, the forging pressure increases by the same amount of the applied back pressure. With more than 98 MPa, the forging pressure increases further due to an increased friction at the hub side. 3. Die temperatures higher than approximately 670k are needed in order to consolidate well the hub top without cracks.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.92-98
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• 1996

Al-Fe alloy layers on heated steel sheet were made by Al powder spray for 30 minutes at $700^{\circ}C$, $800^{\circ}C$ and $1000^{\circ}C$, respectively. As a results, for alloy layers formed at $700^{\circ}C$ and $800^{\circ}C$, main phases were brittle phase $FeAl_3 and Fe_2Al_5$, hardnesses were very high (Hv 700~800), corrosion resistances were good and surfaces were smooth, but wear resistances were bad. For alloy layer formed at $1000^{\circ}C$, main phase was ductile phase $Fe_3Al$, hardness was low (Hv 300~400), corrosion and wear resistances were excellent, but surface was rough. Therefore, alloy layers that formed at $700^{\circ}C$ and $800^{\circ}C$ were heat treated at $1000^{\circ}C$ for 10 minutes for the purpose of smooth surface and excellent wear resistance in this study. It was investigated that brittle phase $FeAl_3 and Fe_2Al_5$ of alloy layers fromed by Al powder spray at $700^{\circ}C$ and $800^{\circ}C$ turn into ductile phase $Fe_3Al$ by heat treated at $1000^{\circ}C$ for 10 minutes without changing smooth surface. It was concluded that the alloy layers formed by Al powder spray on heated steel sheet at $700^{\circ}C$ and $800^{\circ}C$ for 30 minutes and heat treated at $1000^{\circ}C$ for 10 minutes were excellent on wear and smooth surface.

• Journal of Powder Materials
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• v.1 no.2
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• pp.145-152
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• 1994

Atomizing mode and powder characteristics of CuA1Ni base shape memory alloy in rotating disk atomization were investigated in accordance with disk materials and additional elements. Produced powders were classified into two types of spherical and flake shape. In the case of CuAlNiBTi and CuAlNiZr alloy, high yield rate and fine powder were obtained. This tendency was same when we used oxide coated disks. We concluded that this results were steno from the wetting characteristics change between molten metal and disk surface. Especially, due to the reactive properties of Ti and Zr with ceramic disk, the change of atomizing appearance and powder characteristics were noticeable.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.134-135
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• 2006

Ancorsteel 4300, a high performance Cr-Si-Ni-Mo steel, was unveiled two years ago as the first in a series of powder metallurgy alloys that will simulate wrought steel compositions. Advantages of this alloy include good compressibility, high hardenability, and excellent dimensional stability. More important, however, is that this alloy has the ability to be effectively sintered at $1120^{\circ}C$ and maintain oxygen contents below 500 ppm. This unique blend of performance and processing capabilities provides static and dynamic properties that exceed those of conventional powder metallurgy alloys and approach wrought gearing materials. A second Cr-Si-Ni-Mo alloy has now been developed that offers complimentary performance levels at a lower Mo content. This manuscript reviews properties of the two chromium steels with comparisons to traditional sinter-hardened and heat-treated powder metallurgy alloys.

• Journal of Powder Materials
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• v.27 no.1
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• pp.31-36
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• 2020

Phosphorus is an element that plays many important roles in powder metallurgy as an alloy element. The purpose of this study is to investigate the influence of phosphorus addition on the microstructures and mechanical properties of sintered low-alloy steel. The sintered low-alloy steels Fe-0.6%C-3.89%Ni-1.95%Cu-1.40%Mo-xP (x=0, 0.05, 0.10, 0.15, 0.20%) were manufactured by compacting at 700 MPa, sintering in H₂-N₂ at 1260 ℃, rapid cooling, and low-temperature tempering in Ar at 160 ℃. The microstructure, pore, density, hardness, and transverse rupture strength (TRS) of the sintered low-alloy steels were evaluated. The hardness increased as the phosphorus content increased, whereas the density and TRS showed maximum values when the content of P was 0.05%. Based on microstructure observation, the phase of the microstructure changed from bainite to martensite as the content of phosphorus is increased. Hence, the most appropriate addition of phosphorus in this study was 0.05%.

• Journal of Powder Materials
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• v.17 no.2
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• pp.113-122
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• 2010

Two kinds of oxide-dispersion-strengthened (ODS) 316L stainless steel were manufactured using a wet mixing process(wet) and a mechanical alloying method (MA). An MA 316L ODS was prepared by a mixing of metal powder and a mechanical alloying process. A wet 316L ODS was manufactured by a wet mixing with 316L stainless steel powder. A solution of yttrium nitrate was dried after being in the wet 316L ODS alloy. The results showed that carbon and oxygen were effectively reduced during the degassing process before the hydroisostatic process (HIP) in both alloys. It appeared that the effect of HIP treatment on increase in impact energy was pronounced in the MA 316L ODS alloy. The MA 316L ODS alloy showed a higher yield strength and a smaller elongation, when compared to the wet 316L ODS alloy. This seemed to be attributed to the enhancement of bonding between oxide and matrix particles from HIP and to the presence of a finer oxide of about 20 nm from the MA process in the MA 316L ODS alloy.