Mg-Si system

On the silicon-rich side of the Ca/Mg/Si systems new phases have additionally been foimd. According to the Zintl-Klemm concept they must have a higher mean bond order than those discussed previously. 

Al-Mg (5000 Series) and Al-Mg-Si (6000 Series) In the binary alloy system strength is obtained mainly by strain hardening. Stress corrosion is thought to be associated with a continuous grain boundary film of Mg,Alg which is anodic to the matrix . Air cooling prevents the immediate formation of such precipitates, but they form slowly at ambient temperatures. Thus only low Mg alloys are non-susceptible (Al-3% Mg). Widespread precipitation arising from plastic deformation with carefully controlled heat-treatment conditions can lower susceptibility. Al-5Mg alloys of relatively low susceptibility are subjected to such treatments. Mn and Cr... 

SI (le Systeme International d UniUs) units are used in many countries to express clinical laboratory and serum drug concentration data. Instead of employing units of mass (such as micrograms), the SI system uses moles (mol) to represent the amount of a substance. A molar solution contains 1 mol (the molecular weight of the substance in grams) of the solute in 1 L of solution. The following formula is used to convert units of mass to moles (mcg/mL to pmol/L or, by substitution of terms, mg/mL to mmol/L or ng/mL to nmol/L). 

By comparing the observed chemical abundance ratios to supernova model yields, one can calculate , the ratio of the number of SNe la to SNe II events that fit the observations and the synthesized mass of the elements from the model yields. In a study adopting the same analysis techniques as those performed here, [5] found large values of for a trio of low-a stars of [Fe/H] -2. Employing the abundances derived in this study of stars with comparable metallicities, I find that the metal-poor systems presented here possess a- and iron-peak abundances (and based on Na, Mg, Si and Fe) consistent with those observed in metal-poor stars of the MWG (e.g., [6]). 

Fei Y. and Saxena S. K. (1986). A thermochemical data base for phase equilibria in the system Fe-Mg-Si-O at high pressure and temperature. Phys. Chem. Minerals., 13 311-324. 

Aluminium alloys form one of the most widely used groups of materials in existence. They make products which are often cheap and can be applied to many different areas. Extensive work has been done on the experimental determination of binary and ternary phase diagrams, mainly during the mid-part of this century, and researchers such as Phillips (1961) and Mondolfo (1976) have produced detailed reviews of the literature which provide industry standard publications. However, although some important Al-alloys are based on ternary systems, such as the LM2S/ 356 casting alloy based on Al-Mg-Si, in practice they inevitably include small amounts of Cu, Mn, Fe, Ti etc., all of which can significantly modify the castability and properties of the final product. The situation is further exacerbated by the use of scrap material. It is therefore useful to be able to predict phase equilibria in multi-component alloys. 

Experimental work in the systems K-Mg-Si-Al-Fe- O concerning celadonites has also produced expandable minerals (Velde, 1972 Velde, unpublished). In both the muscovite-MgAl celadonite and MgFe-MgAl celadonite compositional series, fully expandable phases were produced below 300°C at 2Kb pressure. These expandable phases can coexist with a potassic feldspar (Figure 23). Their (060) reflection near 1.50 X indicates a dioctahedral structure which can apparently be intimately... 

Dioctahedral montmorillonites with Mg as an interlayer ion in the system Mg-Si-Al-f O have been synthesized at 25°C (Harder, 1972) and 80°C,... 

Figure 30. Comparison range of 7-14 8 chlorite compositions in the Mg-Si-A1 system (Velde, 1973). Dots show composition of berthierine pellets in these coordinates.

Figure 40. Representation of Mg-Si-i O system in terms of the activity of Mg, H+ and aqueous silica (25°C and atmospheric pressure). Solid line boundaries are taken from Wollast, et al., (1968), dashed lines are deduced boundaries based upon the data of Siffert (1962). The appearance of sepiolite is found only above pH 8 and thus the log Mg +/H+ ratio is not valid for all Mg +-H+ values. There are no specified extensive variables or inert components in the system described. Br = brucite M03 = trioctahedral montmorillonites Sep = sepiolite T = talc.

The use of the "closed system" to describe the assemblages in these closed basins seems justified in that frequently, most always, in fact, the number of clay minerals present in the sediments discussed above is two or more. The omnipresence of amorphous silica or chert raises the total number of phases to three. In an essentially three-component system, Mg-Si-Al or possibly four if H+ is considered, this indicates that the chemical components of the minerals are present in relatively fixed quantities in the chemical system which produces the mineral assemblages. None of the first three components is "mobile", i.e., its activity is independent of its relative mass in the solids or crystals present. However, there are sediments which present a monophase assemblage where only one variable need be fixed. Under these conditions sepiolite can be precipitated from solution and pre-existing solid phases need not be involved. 

D.K. Kuel, USP 3381473(1968) CA 69, 20837f(1968) (High-energy fuel systems suitable for use in Dynamites, expl slurries and hybrid rocket systems are described. As fuels Zr, Mg,.Si, Ti, Cr and particularly Be,... 

Crystallisation of glasses in the Nd-Mg-Si-O-N system to form glass-ceramic composites has been investigated. Morrissey et al. (1990) showed that heat treatment at a single temperature resulted in only a small increase in hardness for a 12 24 64 Nd Mg Si composition, but two-stage heat treatments resulted in a much higher increase. They found that the optimum nucleation temperature was related to the glass transition temperature of the materials (usually 7g... 

Among the base units of the SI system, the kilogram unit of mass is the only one whose name, for historical reasons, contains a prefix Qdlo-). Names and symbols for multiples of the unit of mass are formed by attaching prefix names to the unit gram and prefix symbols to the unit symbol g. For example, 1(T kg = 1 mg (1 milligram) but not Ipkg (1 microkilogram). 

---