Mechanical Properties and Microstructural Evolution of Simulated Heat-Affected Zones in Wrought Eglin Steel
Abstract not provided
Leister, Brett M.↗
SEARCH · Engineering Papers
Results for “Microstructural properties”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Investigation on Target Erosion and Effect of Deposition Rate on Microstructure and Properties of Sputtered Be Coating
The beryllium coatings were prepared by direct current magnetron sputtering at different powers. The target erosion rate was theoretically predicted on the basis of the conservation of electric charge and mass. The experiment based on weighing method was performed, which verified the theoretical prediction. XRD analysis reveals that the sputter coatings mainly consist of α-Be phase. On increasing deposition rates, the surface morphology shows a transition from a regular equiaxed grain to a cauliflower-like polygrain owing to the irregular arrangement of atoms and bulk diffusion enhancement originating from the sputtering thermal effect. A heterogeneous particulate-induced growth was observed and derived from fallen scrap during the sputtering process. The surface roughness displays a power function with the thickness increment, while the electrical resistivity is reversed with the grain size.
36 MATERIALS SCIENCE↗
Tailoring Microstructure and Properties of a Superelastic Ti–Ta Alloy by Incorporating Spark Plasma Sintering with Thermomechanical Processing
A powder metallurgy Ti–35 at.% Ta alloy was produced using a spark plasma sintering process. The sintered alloy exhibited Ta-rich regions at a sintering temperature of 1100 °C. Complete diffusion of elemental powders was achieved via homogenization heat treatment at 1500 °C for 12 h, but the ductility declined drastically. The brittle behavior of the homogenized sample was due to the high-oxygen content, continuous grain boundary α-phase and high-angle grain boundaries. Excellent mechanical properties were achieved when hot forging was used along with preheating the homogenized specimen at 1100 °C. The mechanisms underlying this phenomenon were suppression of the solid grain boundary α-phase, high fraction of low-angle grain boundaries and dynamic recrystallization. Tensile strength improved to the maximum value of 868 MPa. The strain recovery ratio increased to 90% in the first cycle during a cyclic loading–unloading test. Incomplete strain recovery of the first cycle was due to the presence of the martensite phase (α″).
36 MATERIALS SCIENCE↗
Effect of ECAP Die Angles on Microstructure Mechanical Properties and Corrosion Behavior of AZ80 Mg Alloy
In this article, the effect of channel angles on material properties was investigated during equal channel angular pressing of AZ80 magnesium alloy using processing route R at 325 °C processing temperature. Channel angles of 90° and 110° and common corner angle 30° have been considered for this study. It has been revealed that the channel angle has a significant influence on deformation homogeneity, microhardness, ultimate tensile strength, ductility and corrosion behavior of Mg alloys. Investigation with reference to as-received AZ80 Mg alloy indicates 18.47% improvement in UTS and 76.07% enhancement in ductility after processing through 3P-90° and 2P-110° ECAP, respectively. Also, the corrosion rate reduces to 89.47% after processing the sample with 3P-110° ECAP die.
36 MATERIALS SCIENCE↗
Effect of titanium additions upon microstructure and properties of precipitation-strengthened Fe-Ni-Al-Cr ferritic alloys
Not Available
Rawlings, Michael J. S.↗
Microstructures and properties of Ti/TiC composites fabricated by laser-directed energy deposition
Not Available
Radhakrishnan, M.↗
Impact of gamma-ray irradiation on hardened white Portland cement pastes exposed to atmosphere
Samples of matured hardened cement paste were exposed to an environment with gamma-ray irradiation, which induces a natural carbonation process. After a dose of approximately 5 x 10{sup 4} kGy, the physical properties, microstructure, and phase composition of the irradiated hardened cement paste samples are compared with those of reference samples exposed to an identical environment without gamma-ray irradiation. Experiments confirm that aragonite and vaterite are preferentially formed under irradiation and that the bending strength is dramatically increased after gamma-ray irradiation. Based on field-emission scanning electron microscopy observations, X-ray scattering profiles, and water vapor sorption isotherm data, it is concluded that vaterite formed on C–S–H plays a role in strengthening the structure of C–S–H via pseudomorphs.
36 MATERIALS SCIENCE↗
Mechanical properties and microstructure of 316L stainless steel produced by hybrid manufacturing
Hybrid manufacturing is a combination of additive (deposition) and subtractive (machining) manufacturing in a single machine tool. Such a system can be used for near net shape manufacturing and component repair using either similar or dissimilar materials. Integrated into a single system, transition between additive and subtractive manufacturing can occur immediately and be leveraged to generate large components by alternating between the processes. In this investigation, we show how the interleaved capabilities can reduce overall cycle time by up to 68 %, improve average relative elongation to failure by 71 %, and reduce the average relative porosity fraction by 83 % when compared to traditional additive manufactured components. Results from this investigation builds the foundation needed for hybrid manufacturing to be applicable towards the manufacture of large complex components such as nosecones and marine propulsors.
36 MATERIALS SCIENCE↗
Microstructure, mechanical properties and strengthening mechanisms of friction stir welded Kanthal APMT™ steel
Not Available
Sittiho, Anumat↗
Shape memory properties and microstructural evolution of rapidly solidified CuAlBe alloys
In this work, the effects of Be addition on the microstructure and phase transformation temperatures of Cu–12Al–xBe (x = 0.4, 0.5 and 0.6 wt.%) shape memory alloys fabricated by using the arc-melting and melt-spinning techniques have been investigated. X-ray diffraction analysis revealed that the arc-melted alloys consisted of austenitic β{sub 1}, martensitic β{sub 1}′ and γ{sub 2} precipitate phases, whereas melt-spun ribbons were composed of a fully martensitic phase. The average grain size of martensitic phases in melt-spun ribbons was determined by electron microscopy images, showing a decrease with increasing Beryllium (Be) amount. Moreover, it was found that the Be addition in the arc-melted alloys had a distinct effect on the morphology of the γ{sub 2} precipitate phase. Transmission electron microscopy analysis showed that the thickness of martensitic plates in the melt-spun ribbons reduced with increasing Be addition. In a differential scanning calorimeter analysis, no martensitic transformation (M{sub s}) peak was observed in arc-melted alloys, but it was clearly detected in melt-spun ribbons, in which M{sub s} decreased dramatically with increasing Be addition. The improvement in the shape memory ability of melt-spun ribbons was explained in terms of the refinement in grain size and martensitic plates. - Highlights: • The CuAlBe SMAs were produced by means of arc-melter and melt-spinner techniques. • MT was directly obtained in melt-spuns without any intermediate process. • The transformation temperatures decreased with increasing Be amount. • The thickness of martensitic plates in the ribbons reduced with increasing Be. • SMP of CuAl was improved by the addition of Be together with rapid solidification.
36 MATERIALS SCIENCE↗
Effects of Co contents on the microstructures and properties of the electrodeposited NiCo–Zr composite coatings
Highlights: • The novel NiCo–Zr coatings were prepared by electro-deposition. • Surface morphology, crystal structure, grain size and microstrain were examined. • Texture, residual stress and corrosion resistance were investigated. • Addition of Co increased the hardness and corrosion resistance of the coatings. - Abstract: In this study, the NiCo–Zr composite coatings were prepared from the electrolytes with different Co{sup 2+} concentrations by electrodeposition method. The effects of Co contents on the crystal structure, surface morphology, grain size, microstrain and residual stress were examined by X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDX) and atomic force microscope (AFM). The corrosion resistance of the composite coatings was also examined by the potentiodynamic polarization and electrochemical impedance (EIS) measurements. The results revealed that the crystal structures of the coatings were dependent on the Co contents and addition of Co content of 58 wt% resulted in the formation of hexagonal (hcp) Co. The increasing Co contents in the NiCo–Zr composite coatings resulted in the smoother and more compact surface, decreased the grain size and increased the microstrain. The micro-hardness and residual stress also increased with increasing Co contents. The addition of Co increased the corrosion resistance of the NiCo–Zr composite coatings compared with the Ni–Zr coating while the corrosion resistance of the NiCo–Zr composite coatings decreased as the Co contents increased.
36 MATERIALS SCIENCE↗