Fabrication, Structure and Properties of Aluminum-Aluminide Layered Composites

1996 ◽  
Vol 434 ◽  
Author(s):  
D. E. Alman
Keyword(s):  
Layered Structure ◽  
Hot Pressing ◽  
Tensile Tests ◽  
Layered Composite ◽  
Structure And Properties ◽  
Layered Composites ◽  
Heat Treated

AbstractThe fabrication of aluminum-aluminide layered composites by reactive bonding of elemental Al and Ni foils was investigated. It was observed that after hot-pressing, thin Ni foils were converted to NiAl. The as-processed Al-NiAl layered structure could be heat-treated to produce an equilibrium Al-Al3Ni layered composite. Tensile tests revealed that composites could be produced that failed in a “tough” manner and were stronger and stiffer than aluminum.

Tribological Properties and Thermal Conductivity of Si3 N4 / Si3N4-BN Alternate Layered Composites

2006 ◽  
Vol 317-318 ◽  
pp. 363-368
Author(s):  
T. Hirao ◽  
Kiyoshi Hirao ◽  
Yukihiko Yamauchi
Keyword(s):  
Thermal Conductivity ◽  
Friction Coefficient ◽  
Tribological Properties ◽  
Hot Pressing ◽  
Layered Composite ◽  
Test Method ◽  
Ring Test ◽  
Layered Composites ◽  
Si3n4 Layer ◽  
Thermal Conductivities

Alternate layered composites of Si3N4 layers and layers of Si3N4 with 20 vol% of hBN (Si3N4-BN layers) were fabricated and their tribological properties and thermal conductivities were evaluated. The layered composites were fabricated by alternate stacking of a monolithic Si3N4 layer and a Si3N4-BN layer in the form of a green sheet, followed by hot-pressing or annealing. For comparison, Si3N4 and Si3N4 with 10% hBN were fabricated by hot-pressing powder mixtures. Tribological properties were evaluated on the side plane of the composites by a block-on-ring test method under a dry sliding condition and thermal conductivities were evaluated. The layered composites were found to have lower friction coefficients and higher wear resistance than to simple composites. Moreover, for the layered composite with an aligned β-Si3N4, the friction coefficient on the plane composed of faceted hexagonal grains was lower. The layered composite with an aligned β-Si3N4 in the Si3N4 layer, fabricated by annealing for 72 h indicated both a low friction coefficient (0.28) and high thermal conductivity (130 W/mK).

Determination of the transverse shear stress in layered composites

2020 ◽  
Vol 86 (2) ◽  
pp. 44-53
Author(s):  
Yu. I. Dudarkov ◽  
M. V. Limonin
Keyword(s):  
Shear Stress ◽  
Transverse Shear ◽  
Composite Beam ◽  
Layered Composite ◽  
Equivalent Model ◽  
Shear Stresses ◽  
Transverse Shear Stress ◽  
Layered Composites ◽  
Laminate Composites ◽  
Transverse Shear Stresses

An engineering approach to estimation of the transverse shear stresses in layered composites is developed. The technique is based on the well-known D. I. Zhuravsky equation for shear stresses in an isotropic beam upon transverse bending. In general, application of this equation to a composite beam is incorrect due to the heterogeneity of the composite structure. According to the proposed method, at the first stage of its implementation, a transition to the equivalent model of a homogeneous beam is made, for which the Zhuravsky formula is valid. The transition is carried out by changing the shape of the cross section of the beam, provided that the bending stiffness and generalized elastic modulus remain the same. The calculated shear stresses in the equivalent beam are then converted to the stress values in the original composite beam from the equilibrium condition. The main equations and definitions of the method as well as the analytical equation for estimation of the transverse shear stress in a composite beam are presented. The method is verified by comparing the analytical solution and the results of the numerical solution of the problem by finite element method (FEM). It is shown that laminate stacking sequence has a significant impact both on the character and on the value of the transverse shear stress distribution. The limits of the applicability of the developed technique attributed to the conditions of the validity of the hypothesis of straight normal are considered. It is noted that under this hypothesis the shear stresses do not depend on the layer shear modulus, which explains the absence of this parameter in the obtained equation. The classical theory of laminate composites is based on the similar assumptions, which gives ground to use this equation for an approximate estimation of the transverse shear stresses in in a layered composite package.

“Structure and Properties of (Ta1-хZrх)C and (Ta1-хHfх)C Solid Solutions Produced by SHS and Hot Pressing”

2021 ◽  
Author(s):  
V.V. Kurbatkina ◽  
E.I. Patsera ◽  
P.A. Loginov ◽  
T.A. Sviridova ◽  
V.V. Klechkovskaya ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Hot Pressing ◽  
Structure And Properties

scholarly journals Preparation and Properties of Layered SiC-Graphene Composites for EDM

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2916
Author(s):  
Ondrej Hanzel ◽  
Zoltán Lenčéš ◽  
Peter Tatarko ◽  
Richard Sedlák ◽  
Ivo Dlouhý ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Surface Layer ◽  
Positive Influence ◽  
Layered Composite ◽  
Layered Composites ◽  
Good Adhesion ◽  
Electric Discharge Machining ◽  
Layer Sequence ◽  
The Individual ◽  
Scratch Tests

Three and five-layered silicon carbide-based composites containing 0, 5, and 15 wt.% of graphene nanoplatelets (GNPs) were prepared with the aim to obtain a sufficiently high electrical conductivity in the surface layer suitable for electric discharge machining (EDM). The layer sequence in the asymmetric three-layered composites was SiC/SiC-5GNPs/SiC-15GNPs, while in the symmetric five-layered composite, the order of layers was SiC-15GNPs/SiC-5GNPs/SiC/SiC-5GNPs/SiC-15GNPs. The layered samples were prepared by rapid hot-pressing (RHP) applying various pressures, and it was shown that for the preparation of dense 3- or 5-layered SiC/GNPs composites, at least 30 MPa of the applied load was required during sintering. The electrical conductivity of 3-layered and 5-layered composites increased significantly with increasing sintering pressure when measured on the SiC surface layer containing 15 wt.% of GNPs. The increasing GNPs content had a positive influence on the electrical conductivity of individual layers, while their instrumented hardness and elastic modulus decreased. The scratch tests confirmed that the materials consisted of well-defined layers with straight interfaces without any delamination, which suggests good adhesion between the individual layers.

Synthesis and characterization of layered bismuth vanadates

1990 ◽  
Vol 5 (11) ◽  
pp. 2718-2722 ◽  
Author(s):  
K. B. R. Varma ◽  
G. N. Subbanna ◽  
T. N. Guru ◽  
C. N. R. Rao
Keyword(s):  
Curie Temperature ◽  
General Formula ◽  
Layered Structure ◽  
Synthesis And Characterization ◽  
Structure And Properties ◽  
Bismuth Vanadates

Bi2VO5.5 (Bi4O11), which is the vanadium analog of the first member of the Aurivillius family of oxides of the general formula Bi2An−1BnO3n+3, has been prepared and characterized. The vanadate has the expected layered structure and is ferroelectric with a Curie temperature of 720 K. While we have not been able to synthesize the vanadium analog of the n = 2 member of the Aurivillius family, we have examined the structure and properties of a vanadate of the composition Bi2V3O9.

scholarly journals On the Development of an Al4.8 wt% Cu Alloy Obtained from Recycled Aluminum Cans Designed for Thixoforming Process

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Ronan Miller Vieira ◽  
Gianni Ferreira Alves Moreira ◽  
André Itman Filho ◽  
Estéfano Aparecido Vieira
Keyword(s):  
Solution Heat Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Permanent Mold ◽  
Semisolid State ◽  
Globular Microstructure ◽  
Cu Alloy ◽  
Heat Treated ◽  
Aluminum Cans ◽  
Melting And Solidification

This work has focused on the development of a new aluminum alloy containing 4.8 wt% of Cu alloy obtained from recycled aluminium cans designed for thixoforming process. After the step of melting and solidification of the alloy in a metallic permanent mold, samples were solution heat treated at 525°C for times ranging from 2 h to 48 h, quenched in water and followed by natural aging. Results have shown the evolution of hardness so from them solubilization solution heat treatment was chosen for 24 h. The best condition for aging was 190°C during 3 h. With this data pieces were thixoforged at 580°C and 615°C corresponding, respectively, to solid fraction (fs) of 0.8 and 0.6. The optimized T6 temper was applied and tensile tests were performed. The mechanical properties obtained are compatible with those obtained for consolidated alloys processed in semisolid state (SS) and after T6 temper hardness increases from 95 HB to 122 HB and the best results were a tensile strength of 324 MPa ± 10 MPa, yield strength of 257 MPa ± 18 MPa, and an elongation of 7.1%  ±  1%. For alloys designed for thixoforming process, these results are in accordance with what was expected whereas globular microstructure, high ductility, and good performance under cyclic conditions are desirable.

scholarly journals Influence of strain rate and heat treatments on tensile and creep properties of Zn-0.15Cu-0.07Ti alloys

DYNA ◽  
2016 ◽  
Vol 83 (195) ◽  
pp. 77-83 ◽  
Author(s):  
María José Quintana Hernández ◽  
José Ovidio García ◽  
Roberto González Ojeda ◽  
José Ignacio Verdeja
Keyword(s):  
Strain Rate ◽  
Room Temperature ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Strain Rates ◽  
Creep Tests ◽  
Design Problems ◽  
Creep Properties ◽  
Heat Treated ◽  
Zn Alloys

The use of Cu and Ti in Zn alloys improves mechanical properties as solid solution and dispersoid particles (grain refiners) may harden the material and reduce creep deformation. This is one of the main design problems for parts made with Zn alloys, even at room temperature. In this work the mechanical behavior of a Zn-Cu-Ti low alloy is presented using tensile tests at different strain rates, as well as creep tests at different loads to obtain the value of the strain rate coefficient m in samples parallel and perpendicular to the rolling direction of the Zn strip. The microstructure of the alloy in its raw state, as well as heat treated at 250°C, is also analyzed, as the banded structure produced by rolling influences the strengthening mechanisms that can be achieved through the treatment parameters.

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