Amorphous Fe73.5Cu1Nb3Si13.5B9 alloys, prepared by a melt-spinning technique, were annealed at a temperature of 823 K under pressures in the range of 1–5 GPa and ambient pressure. The high pressure experiments were carried out in a belt-type pressure apparatus. The microstructure of the annealed alloys has been investigated by x-ray diffraction, electron diffraction, and transmission electron microscopy. Experimental results show that the initial crystalline phase in these annealed alloys is α-Fe solid solution (named as α-Fe phase below), and high pressure has a great influence on the crystallization process of the α-Fe phase. The grain size of the α-Fe phase decreases with the increase of pressure (P). The volume fraction of the α-Fe phase increases with increasing the pressure as the pressure is below 2 GPa, and then decreases (P>2 GPa). The mechanism for the effects of the high pressure on the crystallization process of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy and latent applications of high-pressure annealing amorphous Fe73.5Cu1Nb3Si13.5B9 alloy have been discussed.

Carbon nitride crystals have been synthesized from C3N4H4 in the presence of a nickel-based alloy or cobalt as a catalyst at high pressure of 7 GPa and temperature of about 1400 °C. Scanning electron microscopy showed rod-like, well-faceted crystals with size of several micrometers, and the N content in these carbon nitride crystals was 47–62%. X-ray diffraction indicated the crystals were composed of α–C3N4 and β–C3N4. The experimental lattice constants of α–C3N4 (a = 6.425 Å, c = 4.715 Å ) and β–C3N4 (a = 6.419 Å, c = 2.425 Å ) agree with ab initio calculations very well.

Interfacial phenomena and microstructure in Ag-Si multilayers with a modulation period of 7.64 nm during annealing from 323 to 573 K were investigated by in situ x-ray diffraction and high-resolution transmission electron microscopy. Uphill and downhill diffusion were observed on annealing. The temperature dependence of the effective diffusion coefficient from 373 K (as to downhill diffusion regime) to 523 K was D e ‫ס‬ 2.02 × 10 −20 exp(−0.24 eV/k B T) m 2 /s. Diffusion of silicon atoms along silver grain boundaries was proposed as the main diffusion mechanism. After annealing, continuous silver sublayers changed to nanometer-sized silver particles (about 4.5 nm) coated completely by amorphous silicon.

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