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Porous titanium nickelide exhibiting the shape “memory” effect has been produced from pressed titanium and nickel (carbonyl and electrolytic) powder mixtures of equiatomic composition by high-temperature vacuum sintering resulting in interdiffusion of its components without the formation of a liquid phase. Use of a carbonyl rather than an electrolytic powder in the starting mixture enables sintered TiNi of better physicomechanical properties to be obtained. Sintered TiNi can find practical application not only as a semifinished product in the manufacture of nonporous parts by hot working but also for the production of parts whose thermomechanical recovery characteristics are their key service properties.

A procedure has been developed for the direct observation of the sintering of uncompacted metal powders in the IMASH-1 high-temperature installation. The mechanism by which metallic contacts between tinned bronze granules are initiated and propagated during heating has been established. It was found that, with increasing rate of heating, the temperature of metal contact formation and granule surface melting decreases, as a result of which it is possible to produce filters with a relatively high tin content of the surface layers of granules.

Conclusions 1.The reduction of thin oxide films can be effectively studied by the method of high-temperature microscopy. From the change in the surface coloring of compacts from oxidized powder, the effect of temperature during heating in a hydrogen atmosphere at a residual pressure of 1–10-1 mm Hg on the thickness of the particle oxide film was established.2.With the method of high-temperature microscopy, it is possible to examine the kinetics of variation in the surface microstructure of compacts during their sintering. The first signs of a change in the relief of the surface microstructure of heated compacts from the series A and B powders were noted at temperatures 150–200° in excess of the reduction temperatures of the starting powders.3.After sintering, compacts from the series A copper powder attained a higher density than compacts from the series B powder when the compacting pressure did not exceed 7 tons/cm2.4.The highest density after sintering was achieved in specimens compacted at a pressure of 5 tons/cm{su2}. This was the optimum compacting pressure for the production of compacts from the series A and B powders.

1.Using the technique of high-temperature metallography, a study was made of the sintering behavior of reduced copper powders. It was established that the temperature range corresponding to the formation and growth of metallic contacts between powder particles depends on the reduction temperature of the powder.2.On the basis of experimental data on contact growth, a quantitative evaluation is made of the coefficients of surface self-diffusion and energy of activation. It is shown that the effective coefficient of surface self-diffusion for a copper powder reduced at a low temperature is an order of magnitude greater than that for a copper powder reduced at a high temperature.3.It was found that the effective value of activation energy for the process of contact growth between reduced copper powder particles does not remain constant as a function of sintering temperature. With rise in sintering temperature, the effective value of activation energy increases as a result of an improvement in the structural equilibrium attained in the surface layers of particles in such powders.

1.Fine waste of rimmed steel and cast iron can be used as a raw material in the manufacture of cheap fine iron powder suitable for the cermet industry.2.The microstructural investigation of this fine waste as well as the chemical analysis showed with an adequate accuracy its condition and proved that it is suitable for the intended purpose; they also made possible the selection of a suitable method for processing this waste to iron powder which can be used as a raw material by the cermet industry.3.It has been shown that in principle it is possible to obtain iron powder: a) from fine waste of rimmed steel by the method used in the reduction of rolling scale and b) from fine waste of liquid cast iron using the hydromechanical and iron ore methods normally employed in processing cast iron chips. Special research is needed to develop the commercial processes for producing iron powder from this waste.