Improvements in Strength and Ductility of Feal-ZrB2 By Rapid Solidification

1990 ◽  
Vol 213 ◽  
Author(s):  
David G. Morris ◽  
Maria A. Morris
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Rapid Solidification ◽  
Cell Walls ◽  
Melt Spinning ◽  
Fine Particles ◽  
Stress And Strain ◽  
Cellular Microstructure ◽  
Temperature Heat ◽  
Strength And Ductility

ABSTRACTFe-35Al alloys containing various amounts of ZrB2 have been prepared by melt spinning and the microstructure and its stability examined. The mechanical properties are evaluated both on as cast materials as well as after high temperature heat treatments. The ZrB2 additions lead to a dramatic increase in hardness and strength. In addition, small amounts of ZrB2 lead to significant increases in ductility. Because the microstructure is fairly stable, these improvements in properties are maintained even after high temperature exposures.Alloys with up to about 1%ZrB2 have the dispersoid particles arranged in an imperfect cellular microstructure after rapid solidification. The cell walls contain many fine particles and are efficient barriers against dislocation propagation. Strain occurs as dislocations escape through gaps in the imperfect cell walls at a stress level that is controlled by the size of these gaps. Ductility is improved since the deformation that results from such controlled strain progression through the material is much more uniform and large stress and strain concentrations are avoided.

scholarly journals Rapid solidification of Ni3Al by Osprey deposition

1991 ◽  
Vol 6 (2) ◽  
pp. 361-365 ◽  
Author(s):  
D.G. Morris ◽  
M.A. Morris
Keyword(s):  
High Temperature ◽  
Rapid Solidification ◽  
Cell Walls ◽  
Melt Spinning ◽  
Solidification Process ◽  
High Temperature Annealing ◽  
Rapid Solidification Process ◽  
Material Fabrication ◽  
Very High ◽  
Segregation Structure

A Ni3Al-based alloy containing Cr is examined after preparation by Osprey deposition. The microstructure consists of solidified spherical regions showing cellular segregation interspersed with regions of finer, equiaxed segregation morphology. The segregation structure is characterized by cell interiors rich in aluminum and poor in chromium, while the cell walls are poor in aluminum and rich in chromium. This segregation pattern is the inverse of that expected, based on earlier melt spinning experience, and is explained in terms of the undercooling of the melt prior to solidification. Very high temperature annealing is required to homogenize the material, despite the use of this rapid solidification process for material fabrication.

Characterization of AM60 Magnesium Alloy Prepared by Rapid Solidification and Plastic Consolidation Technique

2010 ◽  
Vol 667-669 ◽  
pp. 997-1002
Author(s):  
Tomasz Tokarski
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Bulk Material ◽  
Structure Refinement ◽  
Hot Extrusion ◽  
Solidification Process ◽  
Protective Atmosphere ◽  
Material Structure

Magnesium and its alloys are attractive candidates for automotive and aerospace applications due to their relatively high strength and low density. However, their low ductility determined by hcp structure of material results in limitation of plastic deformation processing. In order to improve ductility as well as mechanical properties, structure refinement processes can be used. It is well known that effective refining of the material structure can be achieved by increasing the cooling rate during casting procedures, hence rapid solidification process (RSP) has been experimented for the fabrication of magnesium alloys. The present paper reports an experimental investigation on the influence of rapid solidification on the mechanical properties of AM60 magnesium alloy. In order to obtain RS material melt spinning process was applied in protective atmosphere, resulting in formation of RS ribbons. Following consolidation of the RS material is necessary to obtain bulk material with high mechanical properties, as so hot extrusion process was applied. It was noticed that application of plastic consolidation by hot extrusion is the most effective process to achieve full densification of material. For comparison purposes, the conventionally cast and hot extruded AM60 alloy was studied as well. The purpose of the present study was to investigate in detail the effect of rapid solidification and extrusion temperature on the structure and mechanical properties of the materials.

Microstructure Analysis of Melt-Spun Al3Ti Intermetallics by XRD and EXAFS

1996 ◽  
Vol 460 ◽  
Author(s):  
Jinmin Chen ◽  
W. E. Frazier ◽  
E. V. Barrera
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Melt Spinning ◽  
Composition Range ◽  
Processing Parameters ◽  
Wheel Speed ◽  
Annealing Temperatures ◽  
Melt Spun ◽  
Temperature Heat ◽  
Spinning Process

ABSTRACTIn an effort to expand the composition range over which Al3Ti is stable, various amounts of niobium were substituted for titanium and processed by melt-spinning. Several samples were annealed both at 600°C and 1000°C for 24 hours. The effects of processing parameters such as wheel speed, the amount of niobium, and annealing temperatures on the structure were investigated by XRD and EXAFS. XRD showed that for all the samples the only structure present was DO22-The DO22 structure was stable even after the high temperature heat treatments. By means of EXAFS, niobium atoms were observed to occupy titanium sites in the DO22 structure. Furthermore, in the unannealed samples, increasing wheel speed of the melt spinning process or the niobium concentration tended to distort the crystal structure. It was observed that Ti EXAFS had different results from the Nb EXAFS beyond their occupying similar sites, which suggested there may exist some composition zones, i.e. rich Nb zone or rich Ti zones, although the structures present were still DO22. The samples were found to experience different distortions as a function of annealing temperatures.

scholarly journals High Temperature Mechanical Properties of a Vented Ti-6Al-4V Honeycomb Sandwich Panel

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3008
Author(s):  
Lei Shang ◽  
Ye Wu ◽  
Yuchao Fang ◽  
Yao Li
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cell Walls ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Honeycomb Core ◽  
Compression Performance ◽  
High Temperature Mechanical Properties ◽  
Honeycomb Sandwich ◽  
The Face

For aerospace applications, honeycomb sandwich panels may have small perforations on the cell walls of the honeycomb core to equilibrate the internal core pressure with external gas pressure, which prevent face-sheet/core debonding due to pressure build-up at high temperature. We propose a new form of perforation on the cell walls of honeycomb sandwich panels to reduce the influence of the perforations on the cell walls on the mechanical properties. In this paper, the high temperature mechanical properties of a new vented Ti-6Al-4V honeycomb sandwich panel were investigated. A vented Ti-6AL-4V honeycomb sandwich panel with 35Ti-35Zr-15Cu-15Ni as the filler alloy was manufactured by high-temperature brazing. The element distribution of the brazed joints was examined by means of SEM (scanning electron microscopy) and EDS (energy-dispersive spectroscopy) analyses. Compared to the interaction between the face-sheets and the brazing filler, the diffusion and reaction between the honeycomb core and the brazing filler were stronger. The flatwise compression and flexural mechanical properties of the vented honeycomb sandwich panels were investigated at 20, 160, 300, and 440 °C, respectively. The flatwise compression strength, elastic modulus, and the flexural strength of the vented honeycomb sandwich panels decreased with the increase of temperature. Moreover, the flexural strength of the L-direction sandwich panels was larger than that of the W-direction sandwich panels at the same temperature. More importantly, the vented honeycomb sandwich panels exhibited good compression performance similar to the unvented honeycomb sandwich panels, and the open holes on the cell walls have no negative effect on the compression performance of the honeycomb sandwich panels in these conditions. The damage morphology observed by SEM revealed that the face-sheets and the brazing zone show ductile and brittle fracture behaviors, respectively.

Effect of Rolling Reduction on Microstructure and Mechanical Properties of Mg-9Gd-3Y-0.5Zr Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 223-229 ◽  
Author(s):  
S.Q. Li ◽  
Wei Neng Tang ◽  
Rong Shi Chen ◽  
En Hou Han ◽  
Wei Ke
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Large Scale ◽  
Rolling Reduction ◽  
Industrial Products ◽  
Microstructure And Mechanical Properties ◽  
Strength And Ductility

Rolling processing has been carried out on samples cut from the extruded Mg-9Gd-3Y-0.5Zr seamless tubes. Effects of rolling reduction, 5%, 20% and 70% per pass, on its microstructure and mechanical properties were investigated. The results showed that the strength and ductility varied with increasing rolling passes at different rolling reduction. The strength of the alloy rolled by 5% reduction per pass gradually improved with increasing rolling passes, and its ductility remained basically constant. However, when 20% reduction per pass was applied, the strength and ductility of the alloy after rolling increased at first and then decreased a little after the accumulative strain higher than 52%. Moreover, as reduction reached 70% per pass, macro-cracks were induced when rolling at 420°C, while the samples were rolled at a high temperature of 500°C and a larger reduction of 70% per pass exhibited the mechanical properties comparable to those fabricated by 5% and 20% reduction. This indicated that a relatively higher productivity via rolling as well adequate mechanical properties can reach for the large scale of industrial products.

Effect of Magnesium Addition and Rapid Solidification Procedure on Structure and Mechanical Properties of Al-Co Alloy

2013 ◽  
Vol 58 (2) ◽  
pp. 399-406 ◽  
Author(s):  
M. Zygmunt-Kiper ◽  
L. Błaż ◽  
M. Sugamata
Keyword(s):  
Mechanical Properties ◽  
Flow Stress ◽  
Rapid Solidification ◽  
Fine Particles ◽  
True Strain ◽  
Maximum Flow ◽  
Ingot Metallurgy ◽  
Processing Technologies ◽  
High Deformation ◽  
Magnesium Addition

Tested Al-5Co and Al-5Mg-5Co materials were manufactured using a common ingot metallurgy (IM) and rapid solidification (RS) methods combined with mechanical consolidation of RS-powders and hot extrusion procedures. Mechanical properties of as-extruded IM and RS alloys were tested by compression at temperature range 293-773 K. Received true stress vs. true strain curves were typical for aluminum alloys that undergo dynamic recovery at high deformation temperature. It was found that the maximum flow stress value for Al-5Mg-5Co alloy was much higher than that for Al-5Co, both for IM and RS materials tested at low and intermediate deformation temperatures. The last effect results from the solid solution strengthening due to magnesium addition. However, the addition of 5% Mg results also in the reduction of melting temperature. Therefore, the flow stress for Al-5Mg-5Co alloy was relatively low at high deformation temperatures. Light microscopy observations revealed highly refined structure of RS materials. Analytical transmission electron microscopy analyses confirmed Al9Co2 particles development for all tested samples. Fine acicular particles in RS materials, ∽1μm in size, were found to grow during annealing at 823K for 168h. As result, the hardness of RS materials was reduced. It was found that severe plastic deformation due to extrusion and additional compression did not result in the fracture of fine particles in RS materials. On the other hand, large particles observed in IM materials (∽20μm) were not practically coarsened during annealing and related hardness of annealed samples remained practically unchanged. However, processing of IM materials was found to promote the fracture of coarse particles that is not acceptable at industrial processing technologies.

Aluminum Nitride fibers from a Thermoplastic Organoaluminum Precursor

1987 ◽  
Vol 108 ◽  
Author(s):  
John D. Bolt ◽  
Fred N. Tebbe
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Thermal Expansion ◽  
High Temperature ◽  
Aluminum Nitride ◽  
Melt Spinning ◽  
Elevated Temperatures ◽  
Fine Particles ◽  
Bulk Ceramic ◽  
Higher Temperature

ABSTRACTA new organoaluminum polymer (EtAINH)n(Et2AlNH2)m·AlEt3 derived from triethylaluminum and ammonia, is thermoplastic at elevated temperatures and a glassy solid at ambient temperature. As a thermoplastic it can be processed in certain shapes, solidified, cured and transformed to dense aluminum nitride with retention of its shape. Aluminum nitride fibers are prepared by melt spinning the polymer, pyrolyzing in ammonia and at high temperature in nitrogen. The AlN microstructure forms as very fine particles at 400–600°C, coarsens at higher temperature, and densifies at 1600–1800 °C into polycrystalline AlN with submicron grains. Mechanical strength, thermal expansion and dielectric constant are consistent with bulk ceramic values. Initial thermal conductivity deduced from composite measurements is 82 W/m°K in fibers containing 0.5 to 1.0 percent oxygen.

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