Fracture Analysis and Mechanical Properties of Magnesium Based Composites

Mechanical properties and microstructure and fracture analysis of a magnesium alloys based composite series with different volume fraction of alumina dispersoid nanoparticles were studied. The initial states of the composites were further treated by severe plastic deformation (SPD) using equal channel angular pressing (ECAP) in order to achieve microstructures with very fine grains of matrix. Microstructure parameters, in particular the matrix grain size, average size of the dispersed particles and their distribution, were observed using optical microscopy. The average grain sizes of MMCs decreased evidently with the increase of the weight percentage of Al2O3 particles additions and ECAP passes. The heat deformation process of such materials, besides the formation of incorporated Al2O3 particles, also leads to the creation of intermetallic compound Mg17Al12. Fracture surfaces after tensile tests at room and elevated temperature were studied by SEM. The fracture of studying materials were characterized as the ductile fracture due to the existence of a large number of dimples.In summary, it has been shown that mechanical properties are affected by lattice, physical parameters of phases within the composite systems. They are also affected by microstructure and substructure, which depend on the technology of compaction and densification.

Download Full-text

The Effect of Equal-Channel Angular Pressing on Microstructure, Mechanical Properties, and Biodegradation Behavior of Magnesium Alloyed with Silver and Gadolinium

Crystals ◽

10.3390/cryst10100918 ◽

2020 ◽

Vol 10 (10) ◽

pp. 918

Author(s):

Boris Straumal ◽

Natalia Martynenko ◽

Diana Temralieva ◽

Vladimir Serebryany ◽

Natalia Tabachkova ◽

...

Keyword(s):

Mechanical Properties ◽

Grain Refinement ◽

Equal Channel Angular Pressing ◽

Fine Particles ◽

Volume Fraction ◽

Galvanic Corrosion ◽

Angular Pressing ◽

Average Grain Size ◽

The Matrix ◽

Mechanical Properties And Corrosion

The effect of equal channel angular pressing (ECAP) on the microstructure, texture, mechanical properties, and corrosion resistance of the alloys Mg-6.0%Ag and Mg-10.0%Gd was studied. It was shown that ECAP leads to grain refinement of the alloys down to the average grain size of 2–3 μm and 1–2 μm, respectively. In addition, in both alloys the precipitation of fine particles of phases Mg54Ag17 and Mg5Gd with sizes of ~500–600 and ~400–500 nm and a volume fraction of ~9% and ~8.6%, respectively, was observed. In the case of the alloy Mg-6.0%Ag, despite a significant grain refinement, a drop in the strength characteristics and a nearly twofold increase in ductility (up to ~30%) was found. This behavior is associated with the formation of a sharp inclined basal texture. For alloy Mg-10.0%Gd, both ductility and strength were enhanced, which can be associated with the combined effect of significant grain refinement and an increased probability of prismatic and basal glide. ECAP was also shown to cause a substantial rise of the biodegradation rate of both alloys and an increase in pitting corrosion. The latter effect is attributed to an increase in the dislocation density induced by ECAP and the occurrence of micro-galvanic corrosion at the matrix/particle interfaces.

Download Full-text

The Correlation of Microstructure and Mechanical Properties of In-Situ Al-Mg2Si Cast Composite Processed by Equal Channel Angular Pressing

Materials ◽

10.3390/ma12091553 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1553 ◽

Cited By ~ 6

Author(s):

Mahdi Chegini ◽

Mohammad Shaeri ◽

Reza Taghiabadi ◽

Sajjad Chegini ◽

Faramarz Djavanroodi

Keyword(s):

Mechanical Properties ◽

Uniform Distribution ◽

Equal Channel Angular Pressing ◽

Angular Pressing ◽

Ecap Process ◽

Microstructure And Mechanical Properties ◽

The Matrix ◽

Shear Punch ◽

Average Size

In this paper, the effect of equal channel angular pressing (ECAP) on microstructure and mechanical properties of hypereutectic Al-20%Mg2Si and Al-15%Mg2Si, as well as hypoeutectic Al-10%Mg2Si composites has been investigated. After fabricating the composites by in-situ casting, the composites were processed using the ECAP process up to two passes at room temperature. Microstructural studies have been carried out using a field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. Mechanical properties were also documented using Vickers microhardness and shear punch tests. In the hypereutectic composites, a decrease in the average size of pro-eutectic Mg2Si (Mg2Sip) particles, breakages in eutectic networks, and lengthening of the Al (α) phase in direction of shear bands were observed after the ECAP process. For instance, the average size of Mg2Sip Particles in Al-20%Mg2Si composite reduced from 40 to 17 μm after 2 passes of ECAP. Furthermore, a uniform distribution of Mg2Sip particles was developed in the matrix. In hypoeutectic composite, the ECAP process caused a uniform distribution of eutectic Mg2Si (Mg2SiE) in the matrix that considered a favorable microstructure. Microhardness measurements and shear punch results showed an ascending trend after each pass of ECAP for all specimens. For example, microhardness and shear strength of Al-20%Mg2Si increased from 88 HV and 109 MPa to 119 HV and 249 MPa after two passes indicating 35% and 34% increments, respectively. Density and porosity calculations by Archimedes principle revealed that the density of the composites increased after two passes of ECAP due to the reduction of porosity.

Download Full-text

Severe Plastic Deformation of a Commercial Aluminium-Lithium Alloy (AA8090) by Equal Channel Angular Pressing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.871 ◽

2006 ◽

Vol 503-504 ◽

pp. 871-876 ◽

Cited By ~ 4

Author(s):

Núria Llorca-Isern ◽

P.A. Gonzalez ◽

C.J. Luis-Pérez ◽

I. Laborde

Keyword(s):

Mechanical Properties ◽

Research Work ◽

Tensile Tests ◽

Lithium Alloy ◽

Angular Pressing ◽

Processed Material ◽

The Matrix ◽

Potential Mode ◽

Commercial Aluminium ◽

Nano Grains

The enhanced mechanical properties of crystalline materials are linked to very small grain sizes. The AA8090 is a commercial aluminium lithium alloy is referred in the metallurgical literature by its superplastic behavior linked as well to nano-grains as obtained by ECAP. On this research-work in progress, the 8090 aluminium alloy is studied after being processed in a 400 kN ECAE press up to nine passes through a 90º angle-die at 150 °C following Route A (constant path) at a processing speed of 10 mm/min. The room temperature mechanical properties of the extruded alloy are investigated through hardness measurements and tensile tests. Elastic measurements have been carried out by means of nanoindentation and ultrasonic testing, showing that both texture and nanostructuration of the processed alloy influence on the elastic constant of the processed material. In order to understand the mechanisms involved in the SPD-ECAP process, microstructural characterisation of the alloy has been carried out using different high resolution techniques such as Transmission Electron and Atomic Force Microscopy. TEM results have also been used in order to evaluate grain size evolution. From this analysis it is possible to see that after 4 passages the initial grains have already a high degree of dislocations. Among the characterisation techniques, AFM in the surface potential mode has been used to evaluate discontinuities in the matrix and /or decohesion between matrix and precipitates. After nine ECAP passages, no signs of decohesion at the interface have been observed neither using FEG-SEM nor using AFM.

Download Full-text

Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽

10.3390/met11040548 ◽

2021 ◽

Vol 11 (4) ◽

pp. 548 ◽

Cited By ~ 1

Author(s):

Leonid Agureev ◽

Valeriy Kostikov ◽

Zhanna Eremeeva ◽

Svetlana Savushkina ◽

Boris Ivanov ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Elastic Modulus ◽

Strength Properties ◽

Alumina Nanoparticles ◽

Metal Powders ◽

Wide Range ◽

The Matrix ◽

Spark Plasma ◽

Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

Download Full-text

Shape Memory Characteristics and Superelasticity of Ti-Ni-Cu Alloy Ribbons with Nano Ti2Ni Particles

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.d260 ◽

2008 ◽

Vol 8 (2) ◽

pp. 722-727 ◽

Cited By ~ 2

Author(s):

Tae-hyun Nam ◽

Cheol-am Yu ◽

Jung-min Nam ◽

Hyun-gon Kim ◽

Yeon-wook Kim

Keyword(s):

Melt Spinning ◽

Volume Fraction ◽

Deformation Behaviour ◽

Parent Phase ◽

Tensile Tests ◽

Constant Load ◽

Cu Alloy ◽

Transmission Electron ◽

Average Size ◽

Memory Characteristics

Microstructures and deformation behaviour of Ti-45Ni-5Cu and Ti-46Ni-5Cu alloy ribbons prepared by melt spinning were investigated by transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Spherical Ti2Ni particles coherent with the B2 parent phase were observed in the alloy ribbons when the melt spinning temperature was higher than 1773 K. Average size of Ti2Ni particles in the ribbons obtained at 1873 K was 8 nm, which was smaller than that (10 nm) in the ribbons obtained at 1773 K. Volume fraction of Ti2Ni phase in the ribbons obtained at 1873 K was 40%, which was larger than that (20%) in the ribbons obtained at 1773 K. The stress required at temperatures of Af + 10 K for the stress-induced martensitic transformation increased from 93 MPa to 229 MPa and apparent elastic modulus of the B2 parent phase increased from 56 GPa to 250 GPa with increasing the melt spinning temperature from 1673 K to 1873 K in Ti-45Ni-5Cu alloy ribbons. The critical stress for slip deformation of the ribbons increased by coherent Ti2Ni particles, and thus residual elongation did not occur even at 160 MPa, while considerable plastic deformation occurred at 60 MPa in the ribbons without Ti2Ni particles. Almost perfect superelastic recovery was found in the ribbons with coherent Ti2Ni particles, while only partial superelastic recovery was observed in the ribbons without coherent Ti2Ni particles.

Download Full-text

Effect of Aging Treatment on Mechanical Properties and Electrical Conductivity of Cu-5.7%Cr In Situ Composite Produced by Equal Channel Angular Pressing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.560-561.344 ◽

2012 ◽

Vol 560-561 ◽

pp. 344-348 ◽

Cited By ~ 1

Author(s):

Wei Wei ◽

Kun Xia Wei ◽

Igor V. Alexandrov ◽

Qing Bo Du ◽

Jing Hu

Keyword(s):

Mechanical Properties ◽

Electrical Conductivity ◽

Equal Channel Angular Pressing ◽

Aging Treatment ◽

In Situ Composite ◽

Angular Pressing ◽

Peak Aging ◽

Average Size ◽

Equiaxed Grains

The effect of aging treatment on mechanical properties and electrical conductivity of Cu-5.7%Cr in situ composite produced by equal channel angular pressing (ECAP) was investigated here. The rotation and spreading of Cr particles was observed in Cu-5.7%Cr alloy during the ECAP, resulting in long thin in situ filaments. The equiaxed grains of the Cu phase with an average size of 200 nm were developed after eight passes of ECAP. When aging at 400~450 °C for 1 h, Cu-5.7%Cr composite after ECAP shows the maximum microhardness, and the electrical conductivity is larger than 70% of IACS. At 400 °C, the peak aging time appears for 0.5~2 h, dependent on the pre-strain for all ECAP samples. With the increase of ECAP passes, the enhancement of tensile strength due to the aging treatment declines, and even shows negative after eight passes of ECAP. The combination of ECAP and aging treatment would be a promising process to balance mechanical properties and electrical conductivity of Cu-5.7%Cr composite.

Download Full-text

Cellulose Whiskers Micro-Fibers Effect in the Mechanical Proprieties of PP and PLA Composites Fibers Obtained by Spinning Process

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.146.12 ◽

2011 ◽

Vol 146 ◽

pp. 12-26 ◽

Cited By ~ 3

Author(s):

A. Gherissi ◽

R.Ben Cheikh ◽

E. Dévaux ◽

Fethi Abbassi

Keyword(s):

Mechanical Properties ◽

Young’S Modulus ◽

Volume Fraction ◽

Young's Modulus ◽

Tensile Tests ◽

Advanced Materials ◽

Uniaxial Tensile ◽

Failure Resistance ◽

Cellulose Whiskers ◽

Limit Strength

In this study, we present the manufacturing process of two new composites materials in the form of long fibers of polylactic-acid (PLA) or polypropylene (PP), reinforced by cellulose whiskers micro-fibers loads. In order to evaluate the mechanical properties of these advanced materials, a several uniaxial tensile tests were carried out. The PP and the PLA have initially been spinning without the addition of cellulose whiskers micro-fibers. In order to study the effects of cellulose whiskers micro-fibers reinforcements in the Mechanical behavior of the PLA and PP filaments, we determinate the proprieties of these advanced material from the tensile results. For the PP composite filaments material case, the whiskers reinforcement increases Young's modulus and failure resistance, but it reduces the limit strength failure. For the PLA composites the addition of 1% wt of cellulose whiskers from the total volume fraction of the material, increase the Young’s modulus more than 50% and a decrease of the failure resistance and the limit strength of composite. The obtained composites fibers are very rigid and brittle. What follows, that the addition of cellulose whiskers micro fibers in PP matrix, provides mechanical properties more convenient compared to the PLA matrix.

Download Full-text

Strain Rate Effects on Tensile Properties of Fiber Reinforced Concrete

MRS Proceedings ◽

10.1557/proc-64-97 ◽

1985 ◽

Vol 64 ◽

Cited By ~ 7

Author(s):

George G. Nammur ◽

Antoine E. Naaman

Keyword(s):

Reinforced Concrete ◽

Strain Rate ◽

Volume Fraction ◽

Tensile Tests ◽

Fiber Reinforced Concrete ◽

Fiber Reinforced ◽

Steel Fiber Reinforced Concrete ◽

Strain Rate Effects ◽

Rate Effects ◽

The Matrix

ABSTRACTHigh strain rates lead to substantial modifications in the stress-strain (or stress-displacement) response of fiber reinforced concrete in tension. These modifications include higher strength and corresponding strain, as well as smaller displacement at failure.The purpose of this paper is to investigate the behavior of fiber reinforced concrete under impact tensile loading, and to study the effect of strain rate on the post-cracking strength of the composite. The variation of the tensile strength of the matrix with the reinforcement parameters such as volume fraction Vf and aspect ratio |/φ of the fibers is also studied ip this paper. A special emphasis is placed on the stress-displacement relationship of steel fiber reinforced concrete in its post-cracking range. An empirical model of the stress- displacement relationship as a function of the strain rate is developed from experimental data from tensile tests on dogbone shape notched tensile prisms. The model highlights the effects of strain rate and fiber properties on the post-cracking strength of the composite, as well as the displacement at failure. The effect of strain rate on the post-cracking toughness of fiber reinforced concrete is also addressed. The literature on impact effects on concrete in tension (plain and fiber reinforced) is briefly reviewed in this paper, and so is the state of the art of testing techniques for strain rate effects.

Download Full-text

Tensile Behavior of a Glass FRCM System after Different Environmental Exposures

Processes ◽

10.3390/pr8091074 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1074

Author(s):

Jacopo Donnini ◽

Francesca Bompadre ◽

Valeria Corinaldesi

Keyword(s):

Mechanical Properties ◽

Environmental Exposures ◽

Tensile Tests ◽

Chromatography Analysis ◽

The Matrix ◽

Externally Bonded ◽

Open Issue ◽

Flexural Tests ◽

Fabric Reinforced Cementitious Matrix ◽

Inorganic Matrix

The use of Fabric-Reinforced Cementitious Matrix (FRCM) systems as externally bonded reinforcement for concrete or masonry structures is, nowadays, a common practice in civil engineering. However, FRCM durability against aggressive environmental conditions is still an open issue. In this paper, the mechanical behavior of a glass FRCM system, after being subjected to saline, alkaline and freeze–thaw cycles, has been investigated. The experimental campaign includes tensile tests on the fabric yarns, compression and flexural tests on the matrix and tensile tests (according to AC434) on FRCM prismatic coupons. The effects of the different environmental exposures on the mechanical properties of both the constituent materials and the composite system have been investigated and discussed. Ion chromatography analysis has also been performed to better understand the damage mechanisms induced by environmental exposures and to evaluate the ions’ penetration within the inorganic matrix. Alkaline exposure was shown to be the most detrimental for Alkali-Resistant (AR) glass fiber yarns, causing a reduction in tensile strength of about 25%. However, mechanical properties of the FRCM composite seemed not to be particularly affected by any of the artificial aging environments.

Download Full-text

Comparison of Different Heat Treatment Processes of Selective Laser Melted 316L Steel Based on Analysis of Mechanical Properties

Materials ◽

10.3390/ma13173805 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3805 ◽

Cited By ~ 3

Author(s):

Janusz Kluczyński ◽

Lucjan Śnieżek ◽

Krzysztof Grzelak ◽

Artur Oziębło ◽

Krzysztof Perkowski ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Hot Isostatic Pressing ◽

Tensile Tests ◽

Fracture Analysis ◽

Image Correlation ◽

Treatment Processes ◽

Different Types ◽

316L Steel ◽

Precipitation Heat

In this study, we analyzed the mechanical properties of selectively laser melted (SLM) steel obtained via different modifications during and after the manufacturing process. The aim was to determine the effects of precipitation heat treatment on the mechanical properties of elements additively manufactured using three different process parameters. Some samples were additionally obtained using hot isostatic pressing (HIP), while some were treated using two different types of heat treatment and a combination of those two processes. From each manufactured sample, a part of the material was taken for structural analysis including residual stress analysis and microstructural investigations. In the second part of the research, the mechanical properties were studied to define the scleronomic hardness of the samples. Finally, tensile tests were conducted using a digital image correlation (DIC) test and fracture analysis. The treated samples were found to be significantly elongated, thus indicating the advantages of using precipitation heat treatment. Additionally, precipitation heat treatment was found to increase the porosity of samples, which was the opposite compared to HIP-treated samples.

Download Full-text