Download or read book Microstructural Evolution and Mechanical Properties of Cryomilled Nanograined Al 5083 Alloy During Deformation Processing written by Michael K. Apemah and published by . This book was released on 2012 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructural Evolution and Mechanical Properties of Cryomilled Nanograined Near Al 5083 Alloy Following Deformation Processing written by Khan Hasib Kaisar and published by . This book was released on 2014 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructure Evolution and Mechanical Properties of a Heterogeneous Structured Al 5083 Alloy written by Guozhen He and published by . This book was released on 2018 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructure and Mechanical Properties of Aluminum 5083 Processed by Equal Channel Angular Extrusion written by John William Sinclair and published by . This book was released on 1999 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanical Properties and Microstructural Characteristics of an Al Mg Alloy with Bimodal Grain Size at Room and Elevated Temperatures written by Andrew Magee and published by . This book was released on 2012 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: The strength of aluminum alloy 5083 has been shown to be significantly improved when it is engineered to have a bimodal grain size consisting of coarse grains (CGs) embedded in an ultrafine grained (UFG) matrix. This study investigates how a variety of parameters including strain rate, temperature, specimen thickness, CG ratio, and anisotropy affect the mechanical properties of this material when tested in uniaxial tension. The material is fabricated through cryomilling, cold isostatic pressing, and extrusion. A full factorial experiment is designed and implemented to test these effects on the material. Post-test examination of the specimens with optical and electron microscopes is conducted in order to gain a deeper understanding of the material's fracture behavior. While the material shows greatly improved strength compared to conventional Al-Mg alloys at room temperature, its strength rapidly decreases with rising temperature such that by 473 K, it was observed to be weaker than conventional Al 5083 at the same temperature. Dynamic recovery was observed in high temperature tests and the amount of recovery was found to depend on the material's CG ratio. Strain rate sensitivity was observed in the material at all temperatures. Significant differences were observed both in the material's properties and its fracture surface when the specimens were loaded parallel or perpendicular to the extrusion direction. A constitutive model based on Joshi's model of plasticity was developed to describe the material's room temperature behavior.

Download or read book Modeling Microstructural Evolution During Recrystallization of Hot Rolled High Strength Aluminum Alloy 7050 written by Khaled F. M. Adam and published by . This book was released on 2015 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finally, to prove the benefits of integrating the experiment into the simulation model and make the simulation more realistic an initial structure was obtained a real as-deformed microstructure by Electron Back scatter diffraction (EBSD) as well as the second phase particles distribution was determined by Backscattered Electrons (BSE).

Download or read book Behavior and Microstructure in Cryomilled Aluminum Alloy Containing Diamondoid Nanoparticles written by Walid Magdy Tawfik Hanna and published by . This book was released on 2013 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminum (Al) alloys have been the materials of choice for both civil and military aircraft structure. Primary among these alloys are 6061 Al and 5083 Al, which have used for several structural applications including those in aerospace and automobile industry. It is desirable to enhance strength in Al alloys beyond that achieved via traditional techniques such as precipitation hardening. Recent developments have indicated strengthening via grain refinement is an effective approach since, according the Hall-Petch relation, as grain size decreases strength significantly increases. The innovate techniques of severe plastic deformation, cryomilling, are successful in reefing grain size. These techniques lead to a minimum grain size that is the result of a dynamic balance between the formation of dislocation structure and its recovery by thermal processes. According to Mohamed's model, each metal is characterized by a minimum grain size that is determined by materials parameters such as the stacking faulty energy and the activation energy for diffusion. In the present dissertation, 6061 Al and 5083 Al were synthesized using cryomilling. Microstructural characterization was extensively carried out to monitor grain size changes. A close examination of the morphology of the 6061 Al powder particles revealed that in the early milling stages, the majority of the particles changed from spheres to thin disk-shaped particles. This change was attributed to the high degree of plastic deformation generated by the impact energy during ball-powder-ball collisions. Both transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to monitor the change in grain size as a function of milling time. The results of both techniques demonstrated a close agreement with respect to two observations: (a) during cryomilling, the grain size of 6061 Al decreased with milling time, and (b) after 15 h of milling, the grain size approached a minimum value of about 22 nm, which is in the range reported for Al (18 nm -24 nm). Despite this agreement, there was a discrepancy: for grain sizes> 40 nm, the grain size measured by TEM was appreciably larger that inferred from XRD. It was suggested that this discrepancy was most likely related to the limitation for accurately measuring grain sizes> 100 nm by the technique of XRD. It was reported that the average grain size of the as-milled powders of 5083 Al alloy was about 20 nm, and that when the as-milled powders were exposed to elevated temperatures or consolidated via hot isostatic pressing and extruded, the average grain size increased to about 250 nm. Very recent results have indicated the success of maintaining the thermal stability of Al by adding diamantane during milling. 5083 Al powders were cryomilled with 0.5 wt. % diamantane for 8 hours producing mechanically alloyed powders with an average grain size of 17 nm. The grain size remained nanocrystalline (less than100 nm) for Al 5083 alloy with 0.5% diamantane, even after 48 h at the highest temperature of 773 K. The Effect of Diamantane on the thermal stability of cryomilled nanocrystalline 5083 Al alloy was investigated by heating the powder in an inert gas atmosphere at temperature range from 473K to 773K for time interval between 0.5 hr. to 48 hr. The average grain size was observed to be in nano scale range less than 100 nm. The thermal stability results were found to be consistent with the grain growth model based on drag forces exerted by dispersed particles against grain boundary migration (Burke model). As observed for other cryomilled Al alloys, two grain growth regimes were identified using this model: one at relatively low temperatures (473-623 K) where the activation energy is about1.9 kJ/mole and another at higher temperatures where the activation energy is about 18 kJ/mole. The presence of the former region was explained in terms of stress relaxation facilitated by less stable processes such as recovery of dislocation segments or sub-boundary remnants while the latter region was attributed to grain boundary realignment annihilation of grain boundary remnants.

Download or read book Study of Processing and Microstructure of a Superplastic 5083 Aluminum Alloy written by Tracy A. Maestas and published by . This book was released on 2002-09 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orientation Imaging Microscopy (OIM) methods were applied to the analysis of the microstructure and microtexture as well as the deformation and failure modes of superplastic AA5083 aluminum alloys. Annealing of a cold-rolled AA5083 material at 450 deg C resulted in the formation of equiaxed grains approximately 7mum-8mum in size. Random grain-to-grain misorientations were consistent with particle-stimulated nucleation of recrystallization during processing for superplasticity. Such as microstructure is necessary for superplasticity but mechanical property data indicated only moderate ductility and failure by cavity formation and linkage. This investigation then employed OIM methods to identify the misorientations of boundaries prone to cavitation and determine the role of such boundaries in failure of these materials during elevated temperature deformation.

Download or read book The Deformation Characteristics and Microstructural Dynamics of an AL 10MG 0 1ZR Alloy written by and published by . This book was released on 1992 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation into microstructural evolution during processing and superplastic deformation of an Al-10Mg-0.1Zr alloy was conducted. Processing schedules were modified to enhance particle-stimulated nucleation of recrystallization and refine subsequent gain size. Strain rates varying over three orders of magnitude were utilized in subsequent testing of processed material. At lower strain rates of about 10-4 sec-1 coarsening of the microstructure was apparent and elongations of 277% were obtained. A strain rate of 10-3 sec-1 resulted in lesser coarsening and elongations of 650%. A model of deformation by grain boundary sliding in association with microstructural coarsening is presented.

Download or read book Ultrafine grained Aluminum Alloy 5083 and Yttria stabilized Zirconia Metal Matrix Composites written by Matthew James Dussing and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Yttria-stabilized zirconia (YSZ) is of interest as a particle reinforcement in metal matrix composites (MMCs). It possesses high toughness as a result of transformation toughening, along with being an affordable and easily available nanometric powder. Cryomilling was used to produce two batches of aluminum alloy 5083 (AA5083) metal matrix composites incorporating YSZ as the reinforcement, one batch with 2.2 vol.% YSZ (ONR19, MD0, MD0+Ext), and the other with 10 vol.% YSZ (MD1, MD2). For the second batch cryomilling time was reduced from 12 hr to 8 hr, and degassing temperature reduced from 500 °C to 415 °C. Parameters and consolidation methods were varied in the second batch based on lessons learned from the first batch. Chemical reactions between the reinforcement and matrix causing YSZ to decompose and form Al3Zr intermetallics during high temperature processing were studied via differential scanning calorimetry comparison of cryomilled AA5083 with and without YSZ reinforcement. A reaction onset temperature of 420 °C was found when nanometric YSZ was present in the composite. Microstructural characterization of the consolidated materials found YSZ to be well distributed. Grain sizes ranged from a low of 77 ± 41 nm for hot isostatically pressed MD0 material to 362 ± 185 nm for MD0+Ext which had been secondarily processed by extrusion. Mechanical properties were evaluated via tension and compression testing. Ultimate tensile strength (UTS) of 795 MPa with 1.84% strain to failure, and ultimate compressive strength (UCS) of 861 MPa with 10.8+% strain to failure were measured. MD1 material exhibited a 611 MPa UCS with an impressive 22.5% strain to failure. High temperature 400 °C compression test results were exceptional with MD1 retaining 30% of its room temperature strength. Overall, the fabricated materials were found to be sensitive to processing parameters, but strong with good compressive ductility and excellent high temperature strength.

Download or read book The Microstructural Evolution and Mechanical Behavior of Materials in the Extreme Environments of High velocity Impact and Irradiation written by Claire E. Griesbach and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the process-structure-property relations is imperative when designing materials for critical applications, especially when exposed to extreme environments. Clever design of materials containing structural heterogeneities or features spanning multiple length scales can provide synergistically improved properties well beyond the limits of their homogeneous components or provide predictable and acceptable failure modes. In this work, we investigate the process-structure-property relations and the potential for improved performance of materials exposed to the extreme environments of high-velocity impact and irradiation.Similar to material processing techniques such as shot peening and cold spray which induce structural changes through high-velocity impact, we perform well-controlled single microprojectile impact tests of silver (Ag) single crystals which allows for clear correlation of the post-deformation microstructures to the impact-induced plasticity mechanisms. When comparing the impacted microsamples to their pristine single crystal counterparts, we find that the high-strain rates achieved during impact ([epsilon]~108 s-1) induce dramatic structural changes including extensive grain refinement, dislocation density gradients, and a martensitic phase transformation, while the quasi-statically ([epsilon]=10-2 s-1) compressed Ag microcubes remain single crystalline. The impacted samples show a synergistic improvement in strength and toughness, each on average over twice the respective properties of single crystal and bulk polycrystal Ag samples. Such synergistic improvements result from heterogeneous deformation induced stress and strain gradients. Progressive yielding of the gradient grain structure causes enhanced nucleation and pile-up of dislocations in the relatively softer domains to accommodate the elastic-plastic mismatch between grains. The observed dislocation accumulation-which is higher in larger grains-provides ultra-high strain hardening. Additionally, enhanced toughness is achieved through intergranular plasticity mechanisms such as nanograin rotation and grain boundary migration, leading to grain coalescence. These complementary inter- and intragranular plasticity mechanisms elicit improved mechanical properties. We demonstrate the ability to tune the dominant plasticity mechanisms-and thus the resultant properties-through control over the crystal orientation and impact velocity. Our findings provide new understandings of impact-induced nanostructural evolution and mechanistic pathways to improve mechanical properties through heterogeneous deformation, which can be used to improve high strain rate metal processing techniques. The second research thrust examines the effects of structural heterogeneity on the mechanical properties, performance, and failure of tristructural isotropic (TRISO) coated nuclear fuel particles. We examine the irradiation-induced densification and fracture behavior of the porous pyrocarbon buffer layer, which has pronounced effects on the overall particle's performance. Microstructural characterization of the initial as-fabricated buffer layer reveals a gradient of increasing porosity in the radial direction with the porosity reaching a maximum near the buffer-IPyC interface-which is commonly where circumferential tearing initiates in the buffer layer. Using the as-fabricated buffer structure as a basis to investigate the irradiation-induced structural changes, we study the influences of irradiation temperature and fluence on buffer layer response, by characterizing multiple TRISO particles from three different irradiation condition groups. The high temperatures, radiation damage, and mechanical stresses applied to the buffer layer during irradiation cause irradiation condition-dependent micro and nanostructural changes: localized densification near the kernel occurs in particles exposed to relatively lower temperatures, whereas significant changes in the entire pore microstructure occur in particles irradiated under high temperature and fluence. Intriguingly, a large proportion of the total buffer layer densification is accommodated through graphitization of the pyrocarbon rather than the changes in the pore microstructure. Significant nanostructural changes-including an increase in crystallite size, decrease in interplanar spacing, and formation of onion-like graphitic structures-contribute to densification and are most pronounced in the samples exposed to the highest temperature and fluence. Our findings provide a new detailed understanding of the irradiation-induced densification and fracture behavior of the pyrocarbon buffer layer in TRISO nuclear fuel particles, which will enable better predictions of buffer failure, aid in improved future designs, and provide guidance on the acceptable usage of these particles given different reactor conditions.

Download or read book Mechanical Properties and Structural Evolution During Deformation of Fine Grain Magnesium and Aluminum Alloys written by Qi Yang and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deformation Mechanisms Microstructure Evolution and Mechanical Properties of Nanoscale Materials written by Julia Rosolovsky Greer and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Changes in Chemistry and Test Temperature on Deformation Behavior and Fatigue Properties of Al Based Amorphous Alloys written by Chun-Kuo Huang and published by . This book was released on 2011 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: The extraordinary mechanical properties such as high strength, hardness, elasticity, and strength to density ratio, as well as good formability and shaping abilities make Al-based amorphous alloys good candidates for structural applications. In this dissertation, the effects of changes in chemical composition of Al-Gd-Ni-X (X= transition metals) were investigated. Three aspects of properties were examined: thermal stability, deformation behavior, and fatigue properties. Systematic additions of Fe and Co significantly improved Tg and Tx1 of the base Al87Gd6Ni7 amorphous alloy since Fe and Co exhibit a negative heat of mixing with Al. However, the value of (i.e. Tx - Tg) was not changed significantly over the range of alloying additions investigated. The deformation behavior of Al-Gd-Ni-X ribbons was determined by high temperature micro-hardness tests and dynamic mechanical analysis (DMA). Although these ribbons exhibited high hardness/viscosity at room temperature, a distinct reduction near their Tg was observed, with subsequent increases when the test temperature passed Tx. Such behavior and separate TEM analysis indicated that microstructural evolution occurred at this temperature. The deformation behavior also was studied by tensile tests at various temperatures. A transition from inhomogeneous flow to more homogeneous flow was obtained at low strain rates upon approaching Tg, while the deformation behavior at different strain rates and temperatures was captured in a deformation map. In addition, the fatigue performance was examined at both R= -1 and R= 0 conditions. It was demonstrated that the substitution for Al by Fe and Co additions increased the stress amplitude at the fatigue limit from 240 MPa for Al87Gd6Ni7 to 397 MPa for Al86Gd6Ni7Co1 when tested at R= -1. Conducting fatigue tests at R= 0 revealed that tensile mean stresses produced a detrimental effect on the fatigue performance, but not as great as that exhibited in commercial aluminum alloys. It also was demonstrated that the improvement of high cycle fatigue performance of higher alloyed glasses may be a result of their higher Tg, providing a lower value of the ratio of the test temperature to Tg. The importance of this was checked by conducting fatigue tests at lower test temperatures (i.e. different values of T/Tg). The increases in the Fe/Co level that produced improvements in the HCF behavior are partly attributed to the lower T/Tg present during fatigue testing of the highly alloyed ribbons.

Download or read book Heterostructured Materials written by Xiaolei Wu and published by CRC Press. This book was released on 2021-11-24 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterostructured (HS) materials represent an emerging class of materials that are expected to become a major research field for the communities of materials, mechanics, and physics in the next couple of decades. One of the biggest advantages of HS materials is that they can be produced by large-scale industrial facilities and technologies and therefore can be commercialized without the scaling up and high-cost barriers that are often encountered by other advanced materials. This book collects recent papers on the progress in the field of HS materials, especially their fundamental physics. The papers are arranged in a sequence of chapters that will help new researchers entering the field to have a quick and comprehensive understanding of HS materials, including the fundamentals and recent progress in their processing, characterization, and properties.

Download or read book Field Assisted Sintering written by Eugene A. Olevsky and published by Springer. This book was released on 2018-08-09 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book represents the first ever scientific monograph including an in-depth analysis of all major field-assisted sintering techniques. Until now, the electromagnetic field-assisted technologies of materials processing were lacking a systematic and generalized description in one fundamental publication; this work promotes the development of generalized concepts and of comparative analyses in this emerging area of materials fabrication. This book describes modern technologies for the powder processing-based fabrication of advanced materials. New approaches for the development of well-tailored and stable structures are thoroughly discussed. Since the potential of traditional thermo-mechanical methods of material treatment is limited due to inadequate control during processing, the book addresses ways to more accurately control the resultant material's structure and properties by an assisting application of electro-magnetic fields. The book describes resistance sintering, high-voltage consolidation, sintering by low-voltage electric pulses (including spark plasma sintering), flash sintering, microwave sintering, induction heating sintering, magnetic pulse compaction and other field-assisted sintering techniques. Includes an in-depth analysis of all major field-assisted sintering techniques; Explains new techniques and approaches for material treatment; Provides detailed descriptions of spark plasma sintering, microwave sintering, high-voltage consolidation, magnetic pulse compaction, and various other approaches when field-assisted treatment is applied.

Download or read book Advanced Materials written by Ajit Behera and published by Springer Nature. This book was released on 2021-11-21 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a thorough introduction to the essential topics in modern materials science. It brings together the spectrum of materials science topics, spanning inorganic and organic materials, nanomaterials, biomaterials, and alloys within a single cohesive and comprehensive resource. Synthesis and processing techniques, structural and crystallographic configurations, properties, classifications, process mechanisms, applications, and related numerical problems are discussed in each chapter. End-of-chapter summaries and problems are included to deepen and reinforce the reader's comprehension. Provides a cohesive and comprehensive reference on a wide range of materials and processes in modern materials science; Presents material in an engaging manner to encourage innovative practices and perspectives; Includes chapter summaries and problems at the end of every chapter for reinforcement of concepts.