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Title: Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

Abstract

Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rulemore » of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.« less

Authors:
 [1]
  1. Iowa State Univ., Ames, IA (United States)
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1048512
Report Number(s):
IS-T 3040
DOE Contract Number:
AC02-07CH11358
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Kim, Hyong June. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships. United States: N. p., 2011. Web. doi:10.2172/1048512.
Kim, Hyong June. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships. United States. doi:10.2172/1048512.
Kim, Hyong June. Sat . "Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships". United States. doi:10.2172/1048512. https://www.osti.gov/servlets/purl/1048512.
@article{osti_1048512,
title = {Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships},
author = {Kim, Hyong June},
abstractNote = {Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.},
doi = {10.2172/1048512},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 2011},
month = {Sat Jan 01 00:00:00 EST 2011}
}

Thesis/Dissertation:
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  • Metal matrix composites (MMC), especially Al matrix composites, received a lot of attention during many years of research because of their promise for the development of automotive and aerospace materials with improved properties and performance, such as lighter weight and better structural properties, improved thermal conductivity and wear resistance. In order to make the MMC materials more viable in various applications, current research efforts on the MMCs should continue to focus on two important aspects, including improving the properties of MMCs and finding more economical techniques to produce MMCs. Solid state vacuum sintering was studied in tap densified Al powdermore » and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. Microstructures and tensile properties of AYAl-Cu-Fe composites were characterized. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of the matrix choice (elemental Al) and the ''low shear'' consolidation methods utilized. This reinforcement effectiveness is further evidenced by elastic modulus measurements of the composites that are very close to the upper bound predictions of the rule of mixtures. The load partitioning measurements by neutron diffraction showed that composite samples made from GARS powders present significantly higher load transfer efficiency than the composites made from commercially atomized powders. Also, the composite samples made from GARS powders show a higher strengthening effect and ductility than the samples made from commercial purity powders. The higher load transfer efficiency and higher strength and ductility may result from an enhanced inter-particle bonding strength, promoted by the ''clean'' interfaces between particles. Further analysis of the load sharing measurements and the calculated values of the mismatch of coefficient of thermal expansion (CTE) and the geometrically necessary dislocation (GND) effects suggest that these strengthening mechanisms can be combined to predict accurately the strength of the composites.« less
  • This study investigated the processing-structure-properties relationships in an Al/Ca composites using both experiments and modeling/simulation.
  • The successful development of deformation-processed metal-metal composites (DMMC) offers the potential for ductile, high-strength structural materials with high-temperature stability. An infiltration casting process was used to permeate steel wool preforms with molten magnesium-lithium (Mg-Li) alloys. The selected matrix alloys were hexagonal close packed (HCP) Mg-4wt%Li or body centered cubic (BCC) Mg-12wt%Li; the low carbon steel wool fibers were predominantly BCC ferrite. These cast HCP/BCC and BCC/BCC composites were deformed by rolling or by extrusion and swaging. Mechanical properties, microstructure, and texture development of the composites were characterized at various levels of deformation. The HCP/BCC composites had limited formability at temperaturesmore » up to 400 C while the BCC/BCC composites had excellent formability during sheet rolling at room temperature but limited formability during swaging at room temperature. The tensile strengths of these HCP/BCC and BCC/BCC composite materials increased moderately with deformation, though less than predicted from rule of mixtures (ROM) calculations. The microstructure was characterized to correlate the filament size to the deformation strain and mechanical properties of the composite material. Stereological measurements of the filament size were used to adjust ROM calculations to reflect the actual deformation strain in the fibers. However, the experimental strengths of these composite materials were still less than ROM predictions, possibly due to the presence of considerably large fibers. Of the many models used to describe the strengthening observed in DMMC materials, the Hall-Petch relationship adequately described the experimental data. Texture development was also characterized to explain the deformation characteristics of the composite materials. Chapters 2, 3 and 4 are not included here. They are being processed separately.« less
  • The search for high-performance composites that resist delamination when subjected to out-of-plane impacts has prompted an interest in using ductile thermoplastic matrices to replace the current generation of relatively brittle thermoset matrices. There may, however, be a penalty in longitudinal compression strength (LCS). In-situ microscopic observation of five thermoplastic matrix/high-strength, intermediate-modulus carbon-fiber composite found that, although the thermoplastic composites were successful at inhibiting delamination, these materials were relatively weak in response to longitudinal compression. No microscopic evidence of yielding or failure prior to catastrophic compression collapse was found. Micrographs revealing classic microbuckling failure are presented. Current micromechanical models of compositemore » longitudinal compression strength are contradictory about the role of matrix strength and matrix modulus in LCS. These difficulties were overcome in this work by measuring thermoplastic composite LCS as a function of temperature. Thus, matrix properties were changed while microstructural variables were not.« less
  • Composites formed mechanical working of two-phase ductile metal mixtures have received substantial consideration in recent years because of the unique properties they show compared to conventional materials. During mechanical deformation, the two phases deform together, causing the second minor phase to elongate, which results in a fibrous structure within the matrix. Therefore, these composites are referred to as in situ composites or Deformation Processed Metal Matrix Composites (DMMC's). In study, a FCC matrix Al containing HCP Mg will be studied to explore the relationship between properties and microstructures.