Single-phase Fe4N and (Fe1−xNix)4N compounds have been synthesized in a continuous form by heat treating iron and iron-nickel alloy sheets at various temperatures under NH3/H2 atmospheres. The Fe4N sheet has a high room-temperature magnetization value of 179 emu/g (2.14 μB/Fe), which is only slightly less than 218 emu/g (2.19 μB/Fe) observed in pure iron. The magnetic moments of the Fe-Ni alloy nitrides decreased monotonically as x was increased, in contrast to those for the starting alloys Fe1−xNix which exhibited a peak value around x=0.05. The decrease in magnetic moment with nickel content in the alloy nitrides was close to the value anticipated by magnetic dilution from nickel. The coercive force is about 5 Oe and is slightly decreased by the Ni substitution. The Fe-nitride offers a significantly improved corrosion resistance over pure iron. Even further improvement is obtained in the (Fe1−xNix)4N system with only slight sacrifice in magnetic moment. The addition of nickel has been found to noticeably improve the mechanical ductility of the normally brittle Fe4N compound. Theses nitrides also exhibit significantly increased electrical resistivity and wear resistance, and may be useful for a variety of technological applications.

Because of the natural preference for crystal growth in the a-b direction, melt-processed YBCO as well as BSCCO tends to show a local texture with large parallel plates aligned in the direction of CuO2 planes. In YBCO, macroscopically layered and bi-axially textured material can be achieved over extended sample lengths through the use of temperature gradient during melt-texture processing. In BSCCO, a layered structure is relatively easily obtained by subjecting thin ribbon samples in contact with silver to a partial melt processing. While the nature and the mechanism of layer formation may not be the same, the layer configuration in both YBCO and BSCCO is essential for overcoming the grain boundary weak link problem and achieving high transport Jc. In this paper, the process and the mechanism of layer formation will be described, and the implications on superconductor properties will be discussed.