Cu-Fe alloys (CFAs) are much anticipated for use in electrical contacts, magnetic recorders, and sensors. The low cost of Fe has inspired the investigation of these alloys as possible replacements for high-cost Cu-Nb and Cu-Ag alloys. Here, alloys of Cu and Fe having compositions of Cu100-xFex (x = 10, 30, and 50 wt.%) are prepared by gas atomization and characterized microstructurally and structurally based on composition and powder size with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Grain sizes and Fe-rich particle sizes are measured and relationships among composition, powder size, and grain size are established. Same-sized powders of different compositions yield different microstructures, as do differently sized powders of equal composition. No atomic-level alloying is observed in the CFAs under the experimental conditions.

Vacuum degassing is essential in the preparation of RS P/M aluminum alloys to remove adsorbates and for the decomposition of hydrated- on the powder surface. Changes in the surface characteristics during vacuum degassing were investigated by X-ray photoelectron spectroscopy and temperature-programmed desorption measurement. Hydrated- decomposition to crystalline- and hydrogen desorption on the surface of argon gas-atomized aluminum powder occurred at 623 K and 725 K, respectively. This temperature difference suggests that the reaction converting hydrated- to crystalline- during vacuum degassing should be divided into the two reactions .

The microstructure of the extruded Al-20Si bars showed a homogeneous distribution of eutectic Si and primary Si particles embedded in the Al matrix. The grain size of α-Al varied from 150 to 600 nm and the size of the eutectic Si and primary Si in the extruded bars was about 100 - 200 nm. The room temperature tensile strength of the alloy with a powder size <26μm was 322 MPa, while for the coarser powder (45-106μm) it was 230 MPa. With decreasing powder size from 45-106μm to <26μm, the specific wear of all the alloys decreased significantly at all sliding speeds due to the higher strength achieved by ultrafine-grained constituent phases. The fracture mechanism of failure in tension testing and wear testing was also studied.

Al-l4wt.%Ni-l4wt.% Mm(Mm=misch metal) alloy powders rapidly solidified by the gas atomization method were subjected to mechanical milling(MM). The morphology, microstructure and hardness of the powders were investigated as a function of milling time using scanning electron microscopy(SEM), transmission electron microscopy(TEM) and Vickers microhardness tester. Microstructural evolution in gas-atomized Al-l4wt.%Ni-l4wt.% Mm(Mm=misch metal) alloy powders was studied during mechanical milling. It was noted that the as-solidified particle size of decreases during the first 48 hours and then increases up to 72 hours of milling due to cold bonding and subsequently there was continuous refinement to on milling to 200 hours. Two microstructurally different zones, Zone A, which is fine microstructure area and Zone B, which has the structure of the as-solidified powder, were observed. The average thickness of the Zone A layer increased from about 10 to in the powder milled for 24 hours. Increasing the milling time to 72 hours resulted in the formation of a thicker and more uniform Zone A layer, whose thickness increased to about . The TEM micrograph of ball milled powder for 200 hours shows formation of nano-particles, less than 20 nm in size, embedded in an Al matrix.