Phase transformations and structure of eutectic alloys in the Cu-Sn-Ni and Cu-Sn-Ni-Cr systems

Translated from Poroshkovaya Metallurgiya, No. 5(329), pp. 24–28, May, 1990.     

Phase equilibria in nickel-phosphorus and nickel-phosphorus-carbon systems

Conclusions The phase equilibria in the nickel-phosphorus (up to 35% P) and nickel-phosphorus-carbon systems in the area of nickel-rich alloys were investigated by methods of differential thermal, metallographic, and x-ray diffraction analyses. The formation of the phosphides Ni₃P, Ni₉P₂, Ni₁₂P₅, Ni₂P, and Ni₅P₄, was confirmed. The melting points of the phases, the eutectics, and the peritectics were determined more accurately and the temperatures of the polymorphic transformations in Ni₅P₂ and Ni₁₂P₅ were determined for the first time. A non-variant four-phase equilibrium at 860°C was observed in the ternary system. It was established that the addition of phosphorus to alloys of nickel with carbon reduces the temperature of the start of melting from 1318 to 860°C.Translated from Poroshkovaya Metallurgiya, No. 9(285), pp. 78–83, September, 1986.     

Phase equilibria in the systems Zr-Re-B and W-Re-B

Summary Alloys of the systems Zr-Re-B and W-Re-B in the as-cast condition and after quenching from 1500°C, were studied by x-ray diffraction and metallographic techniques. Isothermal sections of these systems were constructed. A compound with a structure of the-Mn type ( phase, a=6.809±0.002 Å) was found in as-cast alloys with 32 at.% W, 63 at.% Re, and 5 at.% B. In the structure of this compound, the W and Re atoms are distributed statistically, while the B atoms fill a quarter of all octahedral voids. The effect of the amount of the third component on the lattice constants of W and Re borides has been established.Translated from Poroshkovaya Metallurgiya, No. 6 (66), pp. 47–53, June, 1968.The authors wish to express their gratitude to P. I. Kripyakevich for valuable discussion of this work.     

Phase transformations in the Al-Li-Hf and Al-Li-Ti systems

Phase transformations in Al-1, 9Li-1.6Hf and Al-1.5Li-0.7Ti (wt pct) alloys have been analyzed thoroughly using various electron microscopy techniques. An Ll₂-ordered ternary Al₃ (Li,X) phase, orά (X), forms in both alloys during heat treatment. Theά forms as spherical precipitates by normal nucleation and growth and in the Hf alloy as filaments by discontinuous precipitation. The X:Li ratio in these precipitates is found to be a function of the precipitation mode in the Hf alloy.ά is coherent with the Al matrix and serves as a preferred nucleation site for the precipitation of the Al₃Li orδ' phase when the alloy is aged at 190°C. Theδ', also Ll₂-ordered, grows as continous envelopes which completely enclose theα' phase. An altered morphology predominates forα'(Ti) after extended heat treatment. The major feature of the altered morphology is the incorporation of spiraled dislocations at theα'/matrix interface, which act to ease the misfit between theα' (Ti) and the matrix.δ' forms as caps on the alteredα'(Ti) in areas away from the dislocations. Disruption of theα' envelopes is attributed to the strain fields and loss of coherency associated with the presence of interfacial dislocations and a possible local shift from Ll₂ to DO₂₂ ordering in theα'(Ti) precipitates.     

Fluid flow in porous systems

Nuclear magnetic resonance (NMR) measurements of water velocity flowing through glass bead packs with a bead diameter of 10 mm have been made using the phi echo-planar imaging (PEPI) sequence. These results indicate that for various flow rates the flow variance is proportional to the mean flow velocity in agreement with the Mansfield-Issa equation. The velocity distributions are approximately Gaussian. Investigation of the slopes of the variance vs. velocity curves as a function of slice thickness indicate some coherence effects in the connectivity of the glass bead system. An extension of an earlier intervoxel coupling model is presented, which seems to explain the observed coherence effects.     

Measurement of flow in infusion systems

The presence of fatty tissue in the myometrium is anomalous; this alteration has been interpreted either as a lipomatous degeneration or as a metaplasia of smooth muscle cells or, still, as a real neoplasm, frequently associated with a leiomyoma, the so-called lipoleiomyoma. The observation of a case of lipoleiomyoma stimulated us to ascertain the real incidence of this lesion which is commonly considered to be rare. We examined 620 single or multiple uterine leiomyomas with extensive sampling of all the areas suspected to contain fatty tissue islands. Five times out of seven the presence of fat cells in a leiomyoma resulted to be a true lipoleiomyoma. It has thus been possible to ascertain the incidence of lipoleiomyoma versus uterine leiomyomatosis (0.8%). Futhermore we observed a prevalence in menopause, an association with multiple leiomyoma and a preferential onset in the subserosa. The pathogenesis of this lesion, which can be fully ascribed to a mixed, benign, heterologous, mesenchymal neoplasm, is briefly discussed.