There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Mechanically alloyed nanocomposites

High strength and thermal stability of bulk Cu/Ta nanolamellar multilayers fabricated by cross accumulative roll bonding

Effects of processing parameters on consolidation and microstructure of W–Cu components by DMLS

Experimental investigations on the synthesis of W–Cu nanocomposite through spark plasma sintering

The influence of the dispersion technique on the characteristics of the W–Cu powders and on the sintering behavior

A mixture of Ta and 20 wt%Cu elemental powders were milled in a high energy mill under two conditions of milling intensity. Composite particles in both conditions were formed. The original Ta particles were firstly fragmented and then pierced in the deformed Cu particles. Cu hardens due to cold work and breaks. The final powder is finer than the initial powders. The final composite particles are homogeneous and consist of amorphous, separated Cu and Ta phases. The more intense milling condition produced composite particles with shorter milling time and amorphization of both phases after 50 h of milling. The less intense milling condition amorphized only the Cu phase. The composite particles can produce denser structures than mixed powders, if heated above the Cu melting point.

Composite Ta–Cu powders prepared by high energy milling

Tantalum is a very interesting metal for industry due to some properties such as high melting point, ductility, high corrosion resistance, besides attractive electric and thermal conductivities. In the present work, the production of metallic tantalum (Ta) has been investigated through the reduction of Ta2O5 by aluminothermic reduction technique (ATR), using hydrogen plasma to trigger the exothermal reaction. Ta2O5 and Al mixtures were previously processed by mechanical alloying during 2, 6 and 10 h. The results obtained by XRD and SEM show that is possible to obtain a compound rich in tantalum through the technique of aluminothermic reduction by plasma.

Franciné Alves Costa

Papers

The influence of the dispersion technique on the characteristics of the W–Cu powders and on the sintering behavior

Composite Ta–Cu powders prepared by high energy milling

Production of tantalum by aluminothermic reduction in plasma reactor

Synthesis of a nanocrystalline composite W–25 wt.%Ag powder by high energy milling

Impact of the SiC addition on the morphological, structural and mechanical properties of Cu-SiC composite powders prepared by high energy milling