PS phase

Poirier G E, Tariov M J and Rushmeier H E 1994 Two-dimensionai iiquid phase and the p phase of aikanethioi seif-assembied monoiayers on Au(111) La/rgmu// 10 3383-6... 

If the concentrations of M" and X" were both the same in the a and P phases, m = m2 this formalism allows for the more general case where the a and P concentrations are not equal. 

Electroneutrality requires simply that the same amounts of positive and negative charge be present in a solution. Applying this separately to both the a and P phases, we obtain... 

Almost every commercial precipitation strengthened aluminum ahoy contains magnesium as an ahoying element. The Al—Mg system (Fig. 13) has a eutectic at 35% magnesium [7439-95-4] Mg, and 451°C. Maximum soHd solubiHty is 14.9% Mg, and solubiHty decreases to about 0.8% Mg at room temperature. Despite this decreased solubiHty, precipitation strengthening by the mestable P -phase precursor to the equhibrium P phase Al3Mg,... 

The SME process can be illustrated by the Cu—Zn system, one of the first SMAs to be studied. A single orientation of the bcc P-phase on cooling goes through an ordering process to a B2 phase. In a disordered alloy, the lattice sites are randomly occupied by both types of atoms, but on ordering the species locate at particular atomic sites, yielding what is called a supedattice. When the B2 phase is cooled below the Mp it transforms to... 

For sodium palmitate, 5-phase is the thermodynamically preferred, or equiUbrium state, at room temperature and up to - 60° C P-phase contains a higher level of hydration and forms at higher temperatures and CO-phase is an anhydrous crystal that forms at temperatures comparable to P-phase. Most soap in the soHd state exists in one or a combination of these three phases. The phase diagram refers to equiUbrium states. In practice, the drying routes and other mechanical manipulation utilized in the formation of soHd soap can result in the formation of nonequilibrium phase stmcture. This point is important when dealing with the manufacturing of soap bars and their performance. 

Tantalum Oxides. Tantalum pentoxide [1314-61 -0] Ta20, (mp = 1880°C, density = 8.73 g/cm ) is a white powder existing in two thermodynamically stable modifications. The orthorombic P-phase changes at 1360°C into the tetragonal a-modiftcation. The existence of an S-modiftcation has also been reported (70). Tantalum pentoxide reacts slowly with hot hydrofluoric acid but is insoluble in water and in most solutions of acids and alkalies. For analytical purposes, it can be dissolved by fusion with alkali hydroxides, alkali carbonates, and potassium pyrosulfate. 

Alloys of the P type respond to heat treatment, are characterized by higher density than pure titanium, and are more easily fabricated. The purpose of alloying to promote the P phase is either to form an aE-P-phase aEoy having commercially useful quaUties, to form aEoys that have duplex a- and P-stmcture to enhance he at-treatment response, ie, changing the a and P volume ratio, or to use P-eutectoid elements for intermetallic hardening. The most important commercial P-aEoying element is vanadium. 

Titanium alloyed with niobium exhibits superconductivity, and a lack of electrical resistance below 10 K. Composition ranges from 25 to 50 wt % Ti. These alloys are P-phase alloys having superconducting transitional temperatures at ca 10 K. Thek use is of interest for power generation, propulsion devices, fusion research, and electronic devices (52). 

Phosphides. Zirconium forms several phosphides ZrP [39318-19-9] 2 [ 12037-80-8] and ZrP g [12066-61 -4]-, they are part of the Zr—P phase diagram (137). The solubiUty of phosphoms in zirconium metal is low, ca 50 ppm, and at higher concentrations it collects as separate globules at the metal grain boundaries. Analysis indicates that this material is Zr P. 

A progressive etching technique (39,40), combined with x-ray diffraction analysis, revealed the presence of a number of a polytypes within a single crystal of sihcon carbide. Work using lattice imaging techniques via transmission electron microscopy has shown that a-siUcon carbide formed by transformation from the P-phase (cubic) can consist of a number of the a polytypes in a syntactic array (41). 

Conditions that favor dezincification include stagnant solutions, especially acidic ones, high temperatures, and porous scale formation (2). Additions of small amounts of arsenic, antimony, or phosphoms can increase the resistance to dezincification. These elements are, however, not entirely effective in preventing the dezincification of the two-phase (cc—P) brasses because dezincification of the P-phase is not prevented (31). Another area of corrosion concern involves appHed or residual stresses from fabrication that can lead to EIC of brasses in the form of stress-corrosion cracking. 

Fig. 2. Equihbtium between vapor and hquid. The conditions for equihbtium are and P =. For a given T and P, phase fugacities are equal,...

An alloy is cooled from a temperature at which it has a single-phase structure (a) to a temperature at which the equilibrium structure is two-phase (a -i- ji). During cooling, small precipitates of the P phase nucleate heterogeneously at a grain boundaries. The nuclei are lens-shaped as shown below. 

Copolymer compositions differ from PVDF in that the crystalline P phase is obtained without mechanical deformation. Thus, various thicknesses of the material can be readily produced. Unfortunately, a reproducible copolymer is not yet commercially available. 

Fig.2. Electron microstructure of the sample hot deformed by 25% a) matrix p phase, b) 7R martensite...

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