Single phase ZrW 2 O 8 was prepared by hydrothermal synthesis via the decomposition of ZrW 2 O 7 (OH 1.5 , Cl 0.5 ) ⋅ 2H 2 O at 570°C. Transmission electron microscopy, in situ high temperature X ray diffraction, and thermogravimetric-differential thermal analyses of synthesized ZrW 2 O 8 were performed. The morphology of the material was represented as rod shaped particles having a block structure. The stabil ity fields of ZrW 2 O 8 were determined. ZrW 2 O 8 demonstrated a negative thermal expansion behavior from 25 to 750°C.

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The paper studied Fe-Ni alloys obtained by sintering from mixtures of powders. Powders with 30-40 wt. Ni were mixed with paraffin and wax binder and then pressed and sintered at 1300 °C during 1 hour. It has been shown that the face centered cubic lattice (γ-phase) and body centered cubic lattice (α-phase) are formed after sintering of powders mixture. The content of the α-phase decreases from 37 % to 2 % with increase of Ni concentration from 30 to 35 wt. % Ni in powders mixture. The average grain size of the γ-phase decreases from 26.5±12.3 μm to 18.3±9.1 μm, and porosity of samples increases from 13±1.4 % to 18.4±1.1 %.The lattice parameter of the γ-phase increases from 3.5849·10−10 m to 3.597·10−10 m and it corresponds to well-known invar alloys. The maximum value of the microhardness of sintered samples is 1.04±0.07 GPa. Thus, alloys obtained by sintering of Fe and Ni powder mixtures has an invar properties typical of cast alloys.