Dynamic material modeling (DMM) analysis has been employed to examine the high strain, elevated temperature mechanical behaviour of Widmanstatten alpha(2) + beta Ti-26Al-10Nb-3V-1Mo. Flow regimes predicted by this ana...
详细信息
Dynamic material modeling (DMM) analysis has been employed to examine the high strain, elevated temperature mechanical behaviour of Widmanstatten alpha(2) + beta Ti-26Al-10Nb-3V-1Mo. Flow regimes predicted by this analysis were then correlated with microstructural observations. Unstable now zones were associated with alpha(2) platelets kinking and shear band formation in the alpha(2) + beta-phase field, with now localization at grain boundaries and dynamic grain growth in the beta-phase field. Stable flow was associated with dynamic spheroidization of the Widmanstatten alpha(2) platelets in the alpha(2) + beta-phase field, and with dynamic recrystallization in the beta-phase field.
Perovskites are important functional materials in modern technology, with numerous applications in optoelectronics, such as solar cells and LEDs, lasers, and other fields. Importantly, the lower Earth mantle is predom...
Perovskites are important functional materials in modern technology, with numerous applications in optoelectronics, such as solar cells and LEDs, lasers, and other fields. Importantly, the lower Earth mantle is predominantly composed of perovskite. (Mg, Fe)SiO 3 and CaSiO 3 , two of the most abundant minerals in the Earth's mantle, are not amenable to being investigated at ambient conditions because they are not stable. CaTiO 3 serves as an excellent analogue. Thus, high-energy laser shock compression was employed to investigate the deformation mechanisms and mechanical behavior of [010] oriented CaTiO 3 under extreme pressure and temperature conditions comparable to those in the mantle, albeit at significantly higher strain rates. The shear stress generated by the 70 GPa shock stress was equal to approximately 20 GPa, assuming elasticity. This is significantly higher than the Peierls-Nabarro stress required to move dislocations, around 10 GPa. In agreement with this, transmission electron microscopy revealed the generation of profuse perpendicular dislocations in [110](001) and [ 1 ¯ 10](001) slip systems. The dislocation density ranged from 15×10 12 m −2 to 2×10 12 m −2 within 12 µm from the shocked surface. Additionally, antiphase domain boundaries along [010] and [100] were observed under the high-pressure shock conditions. CaTiO 3 deforms mainly through dislocation motion due to its positive Clapeyron slope and high atomic packing factor. This study sheds light upon the plastic deformation of (Mg, Fe)SiO 3 and CaSiO 3 , which comprise most of the lower earth mantle.
The surface evolution during dry sliding wear of 2009 Al-20vol.%SiCp on 17-4 PH with differing SiCp sizes (4, 10, 13 and 29 mu m) was investigated. Surface profilometry indicated, independent of composite reinforcemen...
详细信息
The surface evolution during dry sliding wear of 2009 Al-20vol.%SiCp on 17-4 PH with differing SiCp sizes (4, 10, 13 and 29 mu m) was investigated. Surface profilometry indicated, independent of composite reinforcement size, that the roughness (R(a) and R(q)) increased throughout the entire sliding distance, the larger (29 mu m) particulate-reinforced composite showing a tendency for R(a) and R(q) to increase at a higher rate with sliding distance. The larger (29 mu m) particulate-reinforced composite also displayed an R(sk) and R(ku) increase throughout the entire, 3600 m, sliding distance, while a decreasing R(sk) and increasing R(ku) between 360 and 3600 m were observed for the smaller (4, 10 and 13 mu m) particulate-reinforced composites. These results suggest that the lower roughness after 3600 m observed in the small reinforcement composite vis a vis the larger particulate-reinforced composite is the result of a higher degree of peak removal, the valleys not being differently affected between the composites. This difference was attributed to differing third body behavior and wear mechanism between the investigated composites. Scanning electron microscopy showed that the SiC particulate reinforcement debris in the 4 mu m composite were crushed into very fine particles during sliding and acted as a polishing agent while in the 29 mu m composite, the initially larger ceramic debris acted as abrasive particles. Similarly scanning electron microscopy showed that adhesion-induced tribofracture and microcutting were the predominant wear mechanisms at smaller (4, 10, and 13 mu m) reinforcement, while particulate cracking-induced subsurface delamination occurred in the large ceramic (29 mu m) reinforced composites.
References1. J.P. Hirth, R.G. Hoagland and C.H. Popelan. Acta Metall. 32 (1984), p. 371. Abstract | PDF (922 K) | View Record in Scopus | Cited By in Scopus (3)2. R. Thomson and J.E. Sinclair. Acta Metall. 30 (1982),...
详细信息
References
1. J.P. Hirth, R.G. Hoagland and C.H. Popelan. Acta Metall. 32 (1984), p. 371. Abstract | PDF (922 K) | View Record in Scopus | Cited By in Scopus (3)
2. R. Thomson and J.E. Sinclair. Acta Metall. 30 (1982), p. 1325. Abstract | PDF (1072 K) | View Record in Scopus | Cited By in Scopus (11)
3. M.S. Daw and M.I. Baskes. Phys. Rev. B29 (1984), p. 6443. Full Text via CrossRef
4. R.G. Hoagland, M.S. Daw, M. Foiles and M.I. Baskes. J. Mater. Res. 5 (1990), p. 313. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (45)
5. R.G. Hoagland, M.S. Daw and J.P. Hirth. J. Mater. Res. 6 (1991), p. 2565. Full Text via CrossRef
6. J.D. Eshelby. J. Elasticity 5 (1975), p. 321. MathSciNet | Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (167)
7. B. deCelis, A.S. Argon and S. Yip. J. Apply. Phys. 54 (1983), p. 4864. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (70)
8. G.C. Sih and H. Liebowitz. In: (2nd Edition ed.),H. Liebowitz, Editor, Fracture—An Advanced Treatise Vol. II, Academic Press, New York (1968), p. 67.
9. M. Grujicic and P. Dang. In: (2nd Edition ed.),Mater. Sci and Eng. A205 (1996), p. 139. Article | PDF (1329 K) | View Record in Scopus | Cited By in Scopus (17)
10. B. Sundman, private communication, December 1994.
11. M. Grujicic and P. Dang. Mater. Sci. and Eng. A199 (1995), p. 173. Article | PDF (909 K) | View Record in Scopus | Cited By in Scopus (13)
12. W.G. Burgers. Physica 1 (1934), p. 561. Abstract | PDF (2379 K) | View Record in Scopus | Cited By in Scopus (222)
13. M. Grujicic and C.P. Narayan. Mater. Sci. and Eng. A151 (1992), p. 217. Abstract | PDF (611 K) | View Record in Scopus | Cited By in Scopus (8)
AbstractA certain fraction of the mechanical work performed on a specimen is converted into heat during necking of plastic material. A method for measuring this fraction is proposed when specimens are drawn in two dif...
详细信息
AbstractA certain fraction of the mechanical work performed on a specimen is converted into heat during necking of plastic material. A method for measuring this fraction is proposed when specimens are drawn in two different surroundings, air and water. Differences in the heat transfer coefficients of these two media influence the temperature rise during necking. The fraction (α) of mechanical work converted into heat can be calculated using data determined at only one draw rate. The value of α calculated for polypropylene is 0.55 and for polyethylene it is 0.4
As the chiral drug market grows, developing efficient separation methods while ensuring quality has become a key focus for the pharmaceutical industries. Chiral column chromatography is effective but often impractical...
详细信息
The stress and displacement fields of an edge dislocation near a semi-infinite or a finite interfacial crack are formulated by using the complex potential theory of Muskhelishvili's elasticity treatment of plane s...
详细信息
The stress and displacement fields of an edge dislocation near a semi-infinite or a finite interfacial crack are formulated by using the complex potential theory of Muskhelishvili's elasticity treatment of plane strain problems. The image forces exerted on the dislocation have an oscillatory character (with respect to the dislocation position) if the dislocation is originated elsewhere and moves to the vicinity of a finite interfacial crack. There is no such oscillation of image forces if the edge dislocation is emitted from the finite interfacial crack or if the crack is semi-infinite. The stress intensity factors produced by the edge dislocation also have an oscillatory character for both semi-infinite and finite interfacial cracks. They also depend on whether the dislocation is emitted from the crack or comes from elsewhere.
The basic thermodynamic equations governing the equilibrium between (A 1- u B u ) 2- y Te y (s) with y near unity and its liquid and vapor phases are summarized. These are used along with an associated solution model ...
详细信息
The basic thermodynamic equations governing the equilibrium between (A 1- u B u ) 2- y Te y (s) with y near unity and its liquid and vapor phases are summarized. These are used along with an associated solution model for the liquid with species, Hg, Cd, Te, HgTe, and CdTe, to obtain quantitatively good fits to the diverse experimental data. The less extensive data for the Hg-Zn-Te system are also fit and based upon the parameters established, some properties are calculated for which there are no experimental data at present.
In transmission electron microscopy examinations of cast Al matrix-SiC particulate composites, it was noted that a coating of Al4C3 had been formed in contact with some SiC particles. The observed epitaxial orientatio...
详细信息
In transmission electron microscopy examinations of cast Al matrix-SiC particulate composites, it was noted that a coating of Al4C3 had been formed in contact with some SiC particles. The observed epitaxial orientation relationships at the SiC/Al4C3 interface and between the carbides and interfacial Al formed by Al4C3 decomposition are described. The lattice matching between SiC, Al4C3, and reprecipitated Al particles may result in strong bonding and thus permit crack propagation across such interfaces, contributing to the detrimental effects on fracture and fatigue associated with the presence of Al4C3 in aluminum-silicon carbide composites,
The growing shortage of freshwater resources has spurred the development of innovative and sustainable desalination technologies. This study presents a thermo-economic analysis of an innovative hemispherical solar sti...
详细信息
暂无评论