| Design, Analysis and Processing of Functionally Graded Structural Materials |
18 DEC 2000 |
51 pages |
| Authors:
R. J. Diefendorf; J. G. Goree; M. Grujicic; P. F. Joseph; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
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 | A multi-length scale computational methodology is developed to analyze processing/microstructure and microstructure/properties/performance relationship in advanced structural materials. Such methodology is based on combining scientific and engineering disciplines of fluid mechanics, heat transfer, chemical gas/surface thermodynamics and kinetics, atomistic modeling techniques, stochastic microstructure evolution simulation methods, nonlinear fracture and singular stress analysis, and micro-mechanics analytical and computational approaches. This methodology is then applied to advanced coating and functionally graded materials processed ... |
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| Upgrade of Bernex 2000 Chemical Vapor Deposition Reactor |
17 JAN 2000 |
28 pages |
| Authors:
M. Grujicic; CLEMSON UNIV SC
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| A large process-zone Bernex 2000 CVD reactor was donated by DuPont to Clemson University in 1995. Due to lack of funds, the reactor was not activated until Fall 1998. initial runs of the reactor indicated major problems with the pumping system, graphite furnace and the gas/vapor supply systems. Through this project, fluids were obtained to repair the reactor and upgrade it for CVI processing of functionally graded coatings and CVD ... |
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| Atomistic Simulation of Sigma 3 (111) Grain Boundary Fracture in Tungsten Containing Various Impurities |
SEP 1999 |
44 pages |
| Authors:
M. Grujicic; H. Zhao; G. L. Krasko; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The effect of various impurities and micro-alloying additions (B, N, C, O, Al, Si, S, and P) on the intrinsic resistance of the sigma 3 (111) grain boundary in tungsten has been investigated using the molecular dynamics simulation. The atomic interactions have been accounted for through the use of Finnis-Sinclair interatomic potentials. The fracture resistance of the grain boundary has been characterized by computing, in each case, the ideal work ... |
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| A Study of Beta to Alpha'' Martensitic Transformation Volume Change in Ti-Al-V Alloys |
92 |
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| Authors:
M. Grujicic; C. P. Narayan; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
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 | The effect of alloy chemistry on the sign and the magnitude of a volume change accompanying beta-->alpha" martensitic transformation in the Ti- Al-V system is explored using X-ray diffraction; the transformation volume change is found to vary between -4.5 and +4.5%; alloys within the composition range characterized by a large, positive (>+4%) volume change are further studied to explore their potential for dispersed-phase transformation toughening of gamma-titanium aluminide; they are ... |
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| Effect of Iron Additions on Beta-Phase Stability With Respect to Alpha''-Martensite in V-28Al-17Ti(Wt. %) |
92 |
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| Authors:
M. Grujicic; C. P. Narayan; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
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| The effect of iron addition (up to 7 wt.%) on the beta b.c.c.-phase stability with respect to alpha" orthorhombic-martensite and the corresponding transformation volume change in a V-28Al-17Ti (wt.%) alloy has been studied using optical microscopy and X-ray diffraction; it was found that iron additions stabilize the beta phase while the volume change remains positive and relatively high(3-4%); using a liquid nitrogen refrigeration treatment and introducing cracks into the materials ... |
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| Design of Ti-Al-V Beta Phase for Transformation Toughening of Gamma- Titanium Aluminide |
92 |
|
| Authors:
M. Grujicic; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
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| A thermodynamic analysis is developed to determine the chemical composition of the Ti-Al-V gamma phase for dispersed phase transformation toughening of gamm-titanium aluminide. The analysis takes into account the fact that maximum transformation toughening is associated with an optimum level of thermodynamic stability of the beta phase with respect to martensitic transformation and with a large positive value of the beta phase yield martensite transformation volume change. In addition, to ... |
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| Implication of Elastic Coherency in Secondary Hardening of High Co-Ni Martensitic Steels |
91 |
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| Authors:
M. Grujicic; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
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| Composition and stoichiometry of coherent M2C carbide precipitates, (M = Cr, Mo, Fe), in two high Co-Ni martensitic steels have been calculated using thermodynamic conditions for mechanical, chemical and interfacial equilibrium between the ferrite (temper martensite) and the M2C phase; compared to the corresponding incoherent equilibrium compositions, our calculations at the standard secondary hardening temperature of 783 K predict a substantial carbon deficiency and a measurable solubility of iron in ... |
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| Optimization of Ti-Al-V Beta Phase for Dispersed Phase Transformation Toughening of Gamma Titanium Aluminides |
91 |
|
| Authors:
M. Grujicic; C. P. Narayan; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
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| A computer-aided thermodynamic study of the stability of the dispersion, transformation volume change, and beta/gamma chemical compatibility was conducted to determine an optimum composition of the beta-phase dispersion for crack-tip transformation toughening. |
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| Transformation Microyielding of Retained Austenite |
JUN 89 |
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| Authors:
G. N. Haidemenopoulos; M. Grujicic; G. B. Olson; M. Cohen
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| The reversal in the temperature dependence of the elastic limit accurately determines the martensite transformation temperature of retained austenite in 4340 steel. Two models, one based on an exponential distribution of pre-existing nucleation sites and another based on an autocatalytic-site potency distribution, were compared in predicting the constitutive behavior of the steel in the stress-assisted transformation regime. The autocatalytic-site potency distribution is in better agreement with the experimental stress-strain behavior ... |
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| Elastic Moduli, Yield Stress and Ductility of Fully-Crystallized Co(sub 84)Nb(sub 10)B(sub 6) Metallic Glass, |
1986 |
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| Authors:
M. Grujicic; J. Megusar; T. Erturk
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| Annealing of Co(sub 84)Nb(sub 10)B(sub 6) glass for 1 h in the temperature range 973 to 1273 K gave rise to fully-crystallized two-phase material, consisting of a Co-rich matrix and a boride phase with the matrix mean grain size ranging from 31 to 300 nm. The elastic moduli, yield stress and bend ductility of the material were found to depend strongly on the annealing temperature. Young's and shear moduli decreased ... |
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