Production of powders from cast iron swarf and some features of the manufacture of parts from them. I. Production,structure, and properties of the powders

Translated from Poroshkovaya Metallurgiya, No. 7(319), pp. 4–9, July, 1989.     

Development of a technology of compaction of increased-density parts using gas drainage methods. IV. Compaction of powder materials without plasticizer

A new compaction method uses a porous female die made of powdered materials without plasticizer. Powders alloyed with carbon, nickel, chromium, molybdenum, and microtalc were used to produce the porous die. The powder was compacted by a special device, in which the operating surface of the matrix was lubricated through the open pores of the powdered material. Compaction of materials into a porous die ensures highly efficient drainage of gases from the press mold. As a result the density of iron-based compacts increases to 7.4–7.7 g/cm³ and in regard to mechanical properties the sintered materials can compete with those obtained by hot forging.     

Temperature dependence of dielectric function and optical transitions in TlInSe2 and TlGaTe2

The principal components of the dielectric function of TlInSe₂ and TlGaTe₂ crystals with quasi-one-dimensional chain structure have been studied over the photon energies 1.5-5.0eV in the temperature range 140-400 K, with due regard to the reported phase transitions. For TlGaTe₂, the absolute values of the dielectric function experience a sudden temperature-induced change at 290 K in nearly all the accessed photon energy range. The energy and other parameters of the critical points for inter-band optical transitions related to the obtained dielectric function have then been retrieved for both TlInSe₂ and TlGaTe₂. An abrupt change in the energy of the critical point, positioned at 2.93 eV at room temperature and formed by optical transitions induced by the light polarized along the chains, has then been disclosed for TlGaTe₂ at 290 K.