A thermodynamic analysis and calculation of the Fe-Ni-Cr phase diagram

Phase diagrams of Fe-Ni-Cr are calculated as a function of temperature from the liquid phase down to 500 K using thermodynamic values of the pertinent phases. These phases are the liquid, fcc, bcc, sigma, and γ^′-FeNi₃ phases. Not only the thermodynamic values calculated from the models for the various phases are in agreement with experimental data available in the literature, the calculated phase diagrams are also in agreement with experimental data over a wide range of temperature. Below 1123 K, no conventional phase diagram data are available in the literature due to kinetic difficulties. However, the calculated diagram is able to explain the results obtained when the alloys are subjected to electron irradiation. Deceased, was with the Department of Metallurgical and Mineral Engineering, University of Wisconsin.     

基于原子和分子共存理论的Al--Ti熔体反应能力表征

基于原子和分子共存理论建立计算Al-Ti二元合金系结构单元质量作用浓度的热力学模型.利用文献报道的2073、2173和2273 K下Al-Ti二元系的活度计算了生成Al₃Ti、AlTi和Al₁₁Ti₅反应的平衡常数,并进一步得到其标准摩尔吉布斯自由能的表达式.使用文献报道的不同温度下Al-Ti二元合金系全浓度范围内组元Al和Ti的活度a_Al和a_Ti与原子和分子共存理论定义的质量作用浓度N_Al和N_Ti进行比较.结果表明:在Al-Ti二元合金熔体全浓度范围内计算得到的质量作用浓度N_Al和N_Ti与文献报道的活度符合很好.同时,计算得到的Al-Ti二元合金系中结构单元Al₃Ti和Al₁₁Ti₅的平衡物质的量与其质量作用浓度的关系呈"棒状",而结构单元AlTi的平衡物质的量与其质量作用浓度的关系呈"纺锤"形.      

Moment-Based Calculation of Parameters for the Storage Zone Model for River Dispersion

Theoretical methods have been developed to calculate values of parameters of the storage zone model for river mixing. Analytical solutions of the Laplace-transformed equations of the storage zone model are related to the observed concentration distribution in order to determine model parameters in both the moment matching method and the maximum likelihood method, which were developed in this study. The results obtained by comparison with experimental data show that the parameters calculated by the moment matching method are in good agreement with the observed values of storage zone model parameters, whereas results from the maximum likelihood method and several existing methods are not in good agreement with the experimentally observed values. Dispersion data from natural streams show that the calculated concentration curves from the numerical solutions of the storage zone model with the parameters calculated by the moment matching method fit the observed concentration curves very well. It can be concluded that parameters of the storage zone model calculated using the moment matching method can properly explain the natural dispersion processes in real streams.     

圆锥形零件冲压成形皱曲和破裂三极限的预报与控制

根据变形区“多余三角形材料皱曲模型”和防皱曲压边力分别导出外皱曲极限预报与控制判据和内皱曲极限预报与控制判据,以及防外皱曲压边装置的选择判据和防内皱曲压边装置的选择判据。依据破裂模型和拉深变形力导出破裂极限的预报与控制判据,最后给出了圆锥形零件冲压成形皱曲和破裂三极限的预报与控制判据和图形。依据选定的压边力可计算出拉深变形力。实验验证和对比结果证明,将上述判据用于圆锥形零件冲压成形皱曲和破裂三极限的预报与控制是相当准确的     

Energy approach to the problem of calculating the stresses at the initial stages of plastic deformation of crystalline substances and the appearance of structural defects

The critical shear stress and its temperature dependence are calculated for 12 simple substances with different structures and types of bonding. The shear stress for stage II–III of deformation of single crystals (τ^II–III) and σ_{0, y}, i.e., the Hall–Petch relation extrapolated to an infinitely large grain size, are estimated. The energy of formation of lattice defects (vacancies) is calculated using a proposed expression. The results of calculation of the elastic shear energy of a matrix and regions with a high elastic anisotropy are used to estimate the role of elastic anisotropy in lattice stability and fracture. The calculated and experimental results agree satisfactorily with each other.     

Calculation of the temperature induction coefficient of nanostructured hard magnetic Pr-Dy-Gd-Fe-Co-B materials using the molecular-field approximation

Pr-Dy-Gd-Fe-Co-B magnets with low temperature induction coefficients are studied. It is shown that the temperature induction coefficient of a material can be calculated from its composition in the framework of the molecular-field approximation using a model of five magnetic sublattices. The calculated and experimental data are compared.     

Application of Modified QuasiRegular Solution Model to Binary Metallurgical Molten Slag Systems

Modified quasi-regular solution model has been got based on the sub-regular solution model and quasi-regular solution model in this article. The mixed energy parameter can be denoted a function of concentration and temperature. The three parameters of this model are fitted by the computer-assisted analysis based on the experiment data of activity at two different temperatures. Seven binary molten slag systems in the whole concentration are calculated with the application of the model and the average relative error is within 10%. That shows that the calculated result is agreement with the experiment data. Ten binary slag systems presenting saturation concentration are also calculated, but the average relative error is bigger. So the calculated result is not good agreement with the experiment data. But the calculated result is superior to regular solution model, sub-regular solution model and quasi-regular solution model.     

Thermodynamic properties of silicates and of alumino-silicates from montecarlo calculations

Some thermodynamic properties of silicates, aluminates and aluminosilicates have been calculated with the Montecarlo method. This method, developed by Salzburget al, has been applied in the present paper to the calculation of the canonical ensemble partition function. The calculated results are satisfactorily in agreement with the experimental data collected from the literature.     

高炉理论燃烧温度计算的研究

 理论燃烧温度是判断高炉炉缸热状态的重要参数之一。 在深入分析现有理论燃烧温度计算模型存在问题的基础上,提出修正建议 ：绝热系统内除煤气之外还应包括燃料燃烧后的残留物及未燃煤粉;所有物质的比热容应是温度的函数;焦炭的温度应为高温区热平衡计算所得;同时,考察了这些修正因素对理论燃烧温度计算值的影响。     

Thermodynamic calculations of the effective solidification range and its relation to hot cracking of aluminum-based ternary alloys

The correlation between experimental hot cracking (HC) and the calculated effective solidification range (ESR) (obtained as the difference between the formation temperature of a definite amount (65–90 wt %) of the solid phase and the nonequilibrium solidus temperature) is investigated by the example of Al-Cu, Al-Mg, and Al-Si binary systems. It is revealed that the location of the HB peak almost coincides with the calculated ESR peak. A good convergence between the calculated and experimental ESRs is established. The correlation between the HB and calculated ESR is, in general, considerably worse in the studied Al-Cu-Mg, Al-Cu-Si, and Al-Si-Mg ternary systems. It is shown that a correlation between the HB and calculated ESR that is similar to binary systems can be obtained for the radial joins of ternary systems if all alloys compared by the HB are crystallized by identical reactions with the participation of identical phases.     

Desiliconization of a leucoxene concentrate during plasma–arc heating

The parameters of plasma–arc reduction melting of a charge of the carbon-containing leucoxene concentrate from the Yareg deposit are calculated, and the experimental data obtained on the basis of the calculated parameters are presented. Synthetic rutile with 3–4% silicon was synthesized.     

Thermodynamic analysis of the iron-copper system I: The stable and metastable phase equilibria

Thermodynamic and phase diagram data in the Fe-Cu system are evaluated. For the liquid and fcc phases, the Margules-type of equations is used. For the bcc phase, the same type of equation is used to describe the non-magnetic contribution to the Gibbs energy. In addition, a magnetic term is included. Using the thermodynamic equations derived from equilibrium data, the stable and metastable equilibria of this system are calculated. Agreement between the calculated and experimental phase diagram is good except for temperatures higher than 1720 K. For these temperatures, the calculated liquidus tends to be higher. The possibility of supercooling which may account for some of the lower temperatures measured should not be excluded. The calculated metastable miscibility gap of the liquid phase also agrees with the experimental data.     

Mathematical modeling of porosity formation in solidification

Shrinkage porosity and gas porosity occur simultaneously and at the same location when conditions are such that both may exist in a solidifying casting. Porosity formation in a solidifying alloy is described numerically, including the possible evolution of dissolved gases. The calculated amount and size of the porosity formed in Al-4.5 pct Cu plate castings compares favorably with measured values. The calculated distribution of porosity in sand cast Al-4.5 pct Cu plates of 1.5 cm thickness matches experimental measurements. The decrease of the hydrogen content by strong degassing and the increase of mold chilling power are recommended to produce sound aluminum alloy castings. The calculated results for steel plate castings are in agreement with the experimental work of Pellini. The present modeling has clarified the basis of empirical rules for soundness and suggests that the simultaneous occurrence of shrinkage and gas evolution is an essential mechanism in the formation of porosity defects.     

Evaluation of imaging geometries calculated from biplane images

A technique is developed that will calculate accurate and reliable imaging geometries and three-dimensional (3D) positions from biplane images of a calibration phantom. The calculated data provided by our technique will facilitate accurate 3D analysis in various clinical applications. Biplane images of a Lucite cube containing lead beads 1 mm in diameter were acquired. After identifying corresponding beads in both images and calculating their image positions, the 3D positions of the beads relative to each focal spot were determined. From these data, the transformation relating the 3D configurations were calculated to give the imaging geometry relating the biplane views. The 3D positions of objects were determined from the biplane images along with the corresponding imaging geometries. In addition, methods are developed to evaluate the quality of the calculated results on a case-by-case basis in the clinical setting. Methods are presented for evaluating the reproducibility of the calculated geometries and 3D positions, the accuracy of calculated object sizes, and the effects of errors due to time jitter, variation in user-indication, centering, and distortions on the calculated geometries and 3D reconstructions. The precision of the translation vectors and rotation matrices of the calculated geometries were within 1% and 1 degree, respectively, in phantom studies, with estimated accuracies of approximately 0.5% and 0.4 degree, respectively, in simulation studies. The precisions of the absolute 3D positions and orientations of the calculated 3D reconstructions were approximately 2 mm and 0.5 degree, respectively, in phantom studies, with estimated accuracies of approximately 1.5 mm and 0.4 degree, respectively, in simulation studies. This technique will provide accurate and precise imaging geometries as well as 3D positions from biplane images, thereby facilitating 3D analysis in various clinical applications. We believe that the study presented here is unique in that it represents the first steps toward understanding and evaluating the reliability of these 3D calculations in the clinical situation.     

Statistical theory of the hydrogen-induced phase decomposition of an amorphous zirconium-palladium alloy with the formation of metal hydrides. Hydrogen solubility in phases

A statistical theory is developed for the decomposition of an amorphous zirconium-palladium alloy in a hydrogen atmosphere with the formation of metal hydrides. The free energies of the phases are calculated, and equations for the equilibrium states of the phases are derived. The phase-transformation temperatures are determined, and their dependences on the system composition are obtained. The temperature dependences of the hydrogen solubilities in the phases are found, and the appearance of the inflection points or jumps at the phase-transformation points, which are experimentally observed as inflections in the dependences, is grounded. Hydrogen solubility isotherms are calculated, and the possibility of a hysteresis effect is revealed.     

Monte Carlo and analytical calculation of proton pencil beams for computerized treatment plan optimization

Proton pencil beams in water, in a format suitable for treatment planning algorithms and covering the radiotherapy energy range (50-250 MeV), have been calculated using a modified version of the Monte Carlo code PTRAN. A simple analytical model has also been developed for calculating proton broad-beam dose distributions which is in excellent agreement with the Monte Carlo calculations. Radial dose distributions are also calculated analytically and narrow proton pencil-beam dose distributions derived. The physical approximations in the Monte Carlo code and in the analytical model together with their limitations are discussed. Examples showing the use of the calculated set of proton pencil beams as input to an existing photon treatment planning algorithm based on biological optimization are given for fully 3D scanned proton pencil beams; these include intensity modulated beams with range shift and scanning in the transversal plane.     

Calculation of the surface tension of salt melts with divalent ions

The surface tensions of alkaline-earth metal halides and alkali metal sulfates and carbonates are calculated. Molten salts are described in terms of a charged rigid sphere model using the generalized mean spherical approximation. The calculated surface tensions of these salts are compared to the experimental data, and fitting parameters are not used in these calculations.     

板坯的轧制力计算

根据Ｓｉｍｓ公式和由滑移线场理论导出的公式计算板坯轧制力,并采用二维刚塑性有限元法计算了板坯轧制力,所得结果与文献介绍的实验数据相比,其精度较好．     

Prediction of Deformation-Induced γ→α Transformation of 16MnNb Steel

Inpastdecades ,manyresearchershavebeendevelopingatechniquethatcan producelowalloysteelwithferritegrainsizesmallerthan 5 μmsincerefiningthegrainsizeofsteelisthebestwaytoim provebothstrengthandtoughnesssimultaneously .Amongthemsomeresearchershaveproduced 1μmfinegrainedferritesteelthroughthedeformation in ducedtransformation ,i e duringtransformationratherthanafterdeformation[1-3 ] ,andtheirexperi mentshaveshownthatthecombinationofappropri ateaustenitecondition ,deformationconditionandtemperatur…