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Nanocrystalline iron powders were produced by means of gas condensation. Pure nitrogen, or oxygen, or air, was introduced into the as‐made powders before they were taken from the chamber. Different atmospheres produced different layer structures around the iron particles. A high resolution transmission electron microscope was used to analyze the crystal structure and a vibrating‐sample magnetometer was used to measure the magnetic properties of nanocrystalline iron particles. The results showed that a layer of amorphous or nanocrystalline structure was formed initially on the surface of iron particles. This thin amorphous layer crystallized into Fe3O4 after annealing under electron irradiation when the introduced atmosphere was pure oxygen or air. However, it formed a passivated layer of ζ‐Fe2N when nitrogen was introduced. A hydrogen‐reducing process was employed to remove the oxide layer from the surface of nanocrystalline iron particles. The clean surface led to increased magnetization. The exchange an...

Amorphization of TM‐Si (TM: trasition metal) alloy powders by mechanical alloying has been systematically investigated. Pure element powder mixtures were mechanically alloyed for ten hours with a high energy ball mill. The results show that amorphous metallic silicide powders were successfully synthesized in Ti‐Si, Zr‐Si, Nb‐Si, and Ta‐Si systems. Prediction of the amorphization range of mechanically alloyed TM‐Si powders by the Miedema model is inappropriate. The possible criteria for the amorphization of TM3Si powders after mechanical alloying 10 h in a shaker ball mill are (a) the free energy of amorphous state of TM3Si powders is less than −31.95 kJ/mole, and (b) the silicon to trasition metal atomic radius ratio is less than 0.985.

X-ray diffraction and transmission electron microscopy, along with electrical and film stress measurements, were used to evaluate the effectiveness of 40-nm-thick amorphous Ta2N and microcrystalline TaN diffusion barriers, both single and multilayered, against Cu penetration. Failure of the single-layered Ta2N diffusion barrier upon annealing is initialized by crystallization/grain growth, mainly helped by frozen-in compressive stress (3–4 GPa) to transform itself into a columnar structure with a comparable grain size to the thickness of the barrier. However, when subjected to annealing, the Ta2N/TaN alternately layered diffusion barrier with an optimum bilayer thickness (10 nm) remains almost stress-free (0–0.7 GPa) and transforms itself into an equiaxed structure with grain sizes of only ⩽3 nm. Such quasisuperlattice films can present lengthening and complex grained structures to effectively block Cu diffusion, thus acting as much more effective barriers than Ta2N (and TaN) single-layered films.