As-cast alloys

Mg yA1 2> or P-(MgAl). Thus aluminum occurs in magnesium alloys both in soHd solution and as the intermediary intermetaUic phase. The latter is clear white and in slight rehef in poHshed and etched samples. In as-cast alloys, the hard phase occurs in massive form, but when precipitated from sohd solution a lamellar stmcture is formed similar to peadite in steel. When produced by aging at low temperatures, it appears as fine particles. 

Stainless Steel There are more than 70 standard types of stainless steel and many special alloys. These steels are produced in the wrought form (AISI types) and as cast alloys [Alloy Casting Institute (ACI) types]. Gener y, all are iron-based, with 12 to 30 percent chromium, 0 to 22 percent nickel, and minor amounts of carbon, niobium (columbium), copper, molybdenum, selenium, tantalum, and titanium. These alloys are veiy popular in the process industries. They are heat- and corrosion-resistant, noncontaminating, and easily fabricated into complex shapes. 

Figure 2. (b) Formation and lattice parameters of perovskite borides M gPdjB. B content from as-cast alloys ", = La. Ce, Pr, Eu, Gd, Dy. 

A number of investigations on ultrasound effects have been carried out in the U.S. these include studies on vacuum-arc melting of nickel-containing alloys and steels under an ultrasonic field [19], on a mechanism of grain refinement in as-cast alloys [20,23], on amorphization of metals (Suslick [21]), on ultrasonic atomization (Grant [22]), and on production of composite materials [23]. 

It was noted above, that the as-cast eutectic alloys of binary Ti-Si system have no appreciable plasticity at room temperature. Alloying with aluminum, zirconium and use of various modifiers has also not allowed appreciable RT plasticity to be obtained. Data on temperature dependence of mechanical properties of deformed alloys of system Ti-3A1 6Zr-(2-6) Si show that, in contrast to as-cast alloys, deformed state with about 2 % Si demonstrate high plasticity ( 4%) reducing to 1.8 % in alloy with 6-wt.% Si. At the same time high-temperature strength of these alloys are practically the same, at 540-560 MPa level (600 °C). In such a way there is no reason to increase silicon content higher 2-wt.% in deformed state. 

Alloying titanium with silicon is influencing on final structure of as-cast alloy. Interval of silicon content 2-3-wt.% is critical. At the critical amount of silicon the Ti-Si-alloy solidifies with formation of polygonal structure with decreasing grain size at increase of silicon content. At higher silicon content structure of the Ti-Si-alloys is dendritic-eutectic one with the titanium-silicide eutectic between dendrites. 

Data obtained on the extensions of two-phase (Ti) + (TiB) fields are summarized in Table 2. For the as-cast alloys the two-phase regions are more restricted. So, the metal matrix of Ti-Al-B alloys contains the 0C2-phase at composition the Ti85Ali5. 

Raman (1968) investigated the phase equilibria within the concentration section ErAl Si, by means of X-ray powder analysis of as-cast alloys (arc melted) as well as of alloys, annealed for 3 d at 100 °C in evacuated silica tubes (air cooled). Starting materials were Er 99.9%, Al 99.99% and Si 99.99%. ErAlg25 10.75 was observed to crystallize with the CsCl-type of structure with space group Pm3m and a unit cell dimension of a = 3.388(5). The alloys ErAlgjSiy [a = 6.865(5), = 4.307(5), c —... 

Starting from 99.95% Sc, 99.999% Fe and 99.999% Si. Single crystals were obtained from as-cast alloys except in the case of an ScjFeSij alloy which had to be annealed for 1 d at 1100°C and then for 7 d at 1000 °C. The crystallographic data were as follows ... 

Hiebl et al. (1984) studied the structural and magnetochemical behavior within the concentration section Ce(Ru, j OSj )2Si2. A complete solid solution with the ThCrj Si 2-type of structure and symmetry I4/mmm is found to exist. Lattice parameters from X-ray powder data of as-cast alloys were as listed below, table 33. 

Goe] Gddecke, T., Delineation of Crystallization Paths in Ternary As-Cast Alloys (in German), Z. Metallkd., 92(8), 966-978 (2001) (Phase Diagram, Theory, 37)... 

Fra] [1980Fra] Light microscopy, SEM as-cast alloys, up to 14% V and 3.5% C, Near-eutectic alloys... 

The SmNi3Ge3 compound was investigated by the single-crystal method (own structure type, a = 0.4070, c = 2.5137). The single crystal was obtained from as-cast alloy (Mruz 1988). This compound was not observed at 870 K. 

---