Grain boundary prccipitations of tlie BY3 alloy (A1 + 7:4) Zn + l.Y?/, Prlg + 1';; CII + 0.3';; Fe) are studied in the as-annenled state arid after 2"/0 pre-stritining a t room temperature, the alloy being characterized by cqailibriam and non-equilibrium bounclnries. A considerable enliimcenient. of grain boundary precipitates associated with the enhmced activity of grain bonndary diffrisitrri processes is observed in nori-equilibrium grain bonndaries. The knowledge of tlic precipit,xtictii kinetics in x subnii(:ron (0.3 pm) alloy leads to tho conclnsion that such materials arc tlialactcrixed by a high dcgrre of grain boundary lion-equilibrium. liorrig~enxenpr8zipitnt~ion ciner €393-Legierung (A1 + 70/;, Zn + 1,90,b Mg + I Cri + 0Jc>& Fe) iverderi nnmit,telb,zr im ii,iisgchoilten Ziisbnnd iind riach 2% Vorbelastiing bei Zimmertompcratur untcrsticlit, wobei die 1,egierung drircli Gleichgowiclits-und Nichtgleichgeivichtsgrenxcn cliarakt,crixiert ist. Ein bctriiclitliclics Anwachsen der Korngrenzenprazipitate, die mit dcr erliiiliton AktivitSt drs T~orngrcnzcndiffiisioi~s~roz~~sses verlrniipft ist, wird in Niolitgleichgemiclitsgr~~iiz~ii beobachtet. Die I

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Phase transformation points in Li 0.25 Cu 1.75 Se mixed electronic-ionic conductor have been determined by calorimetric, conductometric and thermoelectric measurements. The phase transformation (PT) from triclinic to monoclinic occurs at 403 -413 K. At 503 -515 K the monoclinic phase is followed by a rhombohedral modification. Both of these PTs are accompanied by drops on the calorimetric curve. At about 653 K observed anomalies in the temperature dependencies of the ionic conductivity, of the chemical diffusion coefficient and the jump of the ionic Seebeck coefficient have been induced by the PT to hexagonal phase. Neutron diffraction studies reveal the cubic structure of Li 0.25 Cu 1.75 Se compound (with space group Fm3m) at 773 K. The corresponding PT causes anomalies in the electrical and diffusion properties at 703-713 K. Cu ions are statistically distributed over tetrahedral and trigonal voids in an Fm3m cage; lithium ions randomly occupy 32(f) positions.

Ionic conductivity and chemical diffusion coefficient have been studied for superionic polycrystalline Cu 1.75 Se copper selenide within the temperature interval 300-500 K. An increase in ionic conductivity with an grain size increase is observed. In our opinion, this fact is caused by lower activation energy for the bulk diffusion than that for the grain boundary diffusion.

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