A thermodynamic modeling for the A1-Mn-Si system is conducted via two steps. In the first step, all of the experimental phase diagram and thermodynamic data available from the literature ate Critically reviewed. and several isopleths are constructed by means of X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques. In the second step, a consistent thermodynamic data set for the A1-Mn-Si system over the entire composition and temperature ranges is obtained by consideling reliable literature data and the present experimental results. Numerous comparisons between the calculated and measured phase diagrams as well as thermodynamic quantities indicate that almost all of the reliable experimental information is satisfactorily accounted for by the thermodynamic modeling. The liquidus projection and reaction scheme for the entire system are also presented.

An Al-10Ni-8Y (at.%) alloy was atomized by Ar gas and the morphology, microstructure, thermal stability, phase composition and microhardness of the as-atomized powder were investigated. Most of the powders are spherical in shape, but the surface morphology was different for powder of different size. The cross-section microstructure of powder with size below 15mm in diameter showed no detailed feature, indicating existence of amorphous phase or nanocrystalline structure. The as-atomized powder showed four distinct exothermic peaks when heated at 296, 340, 366 and 456 8C. The glass transition temperature Tg, crystallization temperature Tx, and the temperature interval of the supercooled liquid region DTx (ZTxKTg) were detected to be about 266, 288 and 22 8C. The Al82Ni10Y8 alloy powder exhibits a high Vickers hardness of 230.6, and shows great potential for structural application.

rature five groups of authors [1, 2, 4, 6, 7] reported an eutectic reaction type (L→(Al)+Al45Cr7), whereas the remaining two groups [3, 5] suggested a peritectic one, L+Al45Cr7→(Al). In the phase diagram assessed by Murray [11, 12], the peritectic reaction type is adopted. The purpose of the present work is to identify the degenerated nature for the invariant reaction among (Al), liquid, and Al45Cr7 by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron probe microanalysis (EPMA) methods

The isothermal section at 950℃ of the Co-Nb-Ti system was investigated using diffusion couples and six ternary alloys. The specimens were examined by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. No ternary compound was found. Nine three-phase equilibria were observed. The binary intermediate phases NbCo3 and Nb2Co7, the existence of which is still controversial in the literature, were observed at 950℃. The solubilities of Ti in Nb2Co7, NbCo3, γ-NbCo2 and μ-Nb6Co7 were determined to be 1.9, 16.4, 14.4 and 17.4 at.%, respectively. The solubilities of Nb in TiCo3, TiCo2(h), TiCo2(c), TiCo and Ti2Co were determined to be about 5.7, 11.0, 2.6, 13.6 and 3.1 at.%, respectively.

The thermodynamic database for the Al-Fe-Mg-Mn-Si system is developed based on the constituent binary, ternary, and quarternary systems. The computed phase diagrams agree well with the experimental data. The obtained database is used to describe the solidification behavior of Al 356.1 (91.95Al-0.46Fe-0.3Mg-0.32Mn-6.97Si, in wt.%) and Al 356.2 (92.77Al-0.08Fe-0.35Mg-6.8Si, in wt.%) under equilibrium and Gulliver-Scheil non-equilibrium conditions. The reliability of the established thermodynamic database is also verified by the good agreement between calculation and experiment for both equilibrium and Gulliver-Scheil non-equilibrium solidifications. Microstructure and microsegregation of the directionally solidified Al 356.1 alloy are investigated with a growth rate of 0.04445 cm s-1 and a temperature gradient of 45K cm-1. Fractions of solids formed are measured by using quantitative image analysis of back-scattered electron, and solute redistribution in the primary (Al) is determined by means of an area scan approach with a total of 2400 electron probe microanalysis point counts. A micromodel, which includes solid-state diffusion, secondary dendrite arm coarsening, and dendrite tip and eutectic undercooling, is coupled with a multicomponent phase diagram calculation engine (PanEngine) to predict the microstructure and microsegregation of the solidified alloy. Quantitative agreement of the model prediction with the experiment is obtained for concentration distributions in the primary (Al), the types and amounts of phases formed, and the solidification path.