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Metal based composites by mechanical alloyings

Group 03: MSE K581. Nguyen Hien Trang 2. Tran Van Hiep3. Nguyen Van Tu

Instructor: Dr. Nguyen Hoang Viet

LOGOPurposes Comprehension about metal-based

compositesStructural analysis of Metal Matrix

compositesSEM, EDX, XRD,...

LOGOContents

Background knowledge1

2

Fe- based MMC3

Al-based MMC4

Analysis methods using SEM, XRD….

LOGOI.Background knowledge Definition and classificationsMatrix – reinforcementHardness, porosity measurementResearch methods SEM,EXD….Pros & cons

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DEFINITION & CLASSIFICATIONS- Composite: 2 or more different materials in a macroscopic level that are combined and are not soluble in each other.- Classification: Metal Matrix Composites (MMCs) Polymer Matrix Composites (PMCs) Ceramic Matrix Composites (CMCs)- A metal matrix composite (MMC) = a metal + a different metal or another material (such as a ceramic or organic compound

I.Background knowledge

MMC

Matrix

Metallic

Reinforcements

Non - metallic

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MATRIX - The characteristics of some common matrix

Aluminum Iron CopperYoung modulus

70 GPa 211 GPa 110 – 128 GPa

Density 2.7 g/cm3 7.874g/cm3 8.94 g/cm3

Melting point 6600C 15380C 10840C

Other properties

- Well resistance- Good electrical and thermal conductivity

-Easy to be oxidized

-Excellent electrical and thermal conductivity

Applications Produce piston Produce cutting tools

Produce thermal machines

I.Background knowledge

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Reinforcement

Continuous Discontinuous

Particle Whisker

There are 3 kinds of MMC1. Particale reinforced MMC2. Short fiber (whisker) reinforced MMC3. Continuous fiber/sheet reinforceed MMC

REINFORCEMENTI.Background knowledge

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MEASUREMENT OF HARDNESS Brinell Vicker Rockwell

I.Background knowledge

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MEASUREMENT OF POROSITY

Porosity = ratio between Vpores and V mat.Þ Verify hardness, electrical conductility…- Using Acsimet to determine the density of specimen

- Porosity

I.Background knowledge

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Research methodsThe purpose is to determine what elements are presen1. Energy-dispersive x-ray spectrum

(EDX)- X-radiation is produced when a

specimen is bombarded by high-energy electrons. The beam electrons eject inner-shell electrons that are then replaced by outer-shell electrons. This replacement results in emission of an x ray characteristic for that element. The x-ray energy level is displayed as the number of counts at each energy interval and appears as peaks on a continuous background 

- Peak positions are specific to a particular element

I.Background knowledge

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Research methods2. Xray Diffraction (XRD) 3. Xray spectrometer (XRS)4. X-Ray Fluorescence (XRF) (time, specimen – good)

I.Background knowledge

(A) SEM and (B) TEM images, (C) XRD pattern, and (D) XPS spectrum of 1 kind of composite  

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 PROS & CONS

2

Advantages - High specific modulus, Higher

specific strength- Ductile, strong- Good thermal, electrical

conductility- Better wear resistant

3

Disadvantages - Difficult to fabricate, expensive- Heavier than PMCs

I.Background knowledge

LOGOII. X-ray Powder Diffraction (XRD)What is X-ray Powder Diffraction (XRD)XRD is a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions.PrinciplesX-ray diffraction is based on constructive interference of monochromatic X-rays and a crystalline sample.

LOGOII. X-ray Powder Diffraction (XRD)

Three basic elements: • an X-ray tube• a sample holder• an X-ray detector.

How does it work?

XRD instrumentation

LOGOII. X-ray Powder Diffraction (XRD)

These X-rays are generated by a cathode ray tube, filtered to produce monochromatic radiation, collimated to concentrate, and directed toward the sample

When conditions satisfy Bragg's Law nλ=2d sin θ

LOGOII. X-ray Powder Diffraction (XRD)XRD can be use for:• characterization of crystalline materials• determination of unit cell dimensions• measurement of sample purity• determine crystal structures using Rietveld refinement• determine of modal amounts of minerals• characterize thin films• characterize thin films samples 

LOGOII. X-ray Powder Diffraction (XRD)Strengths• Powerful and rapid (< 20 min) • Get clear results• Minimal sample preparation• XRD units are widely available• Data interpretation is relatively straight forward

Limitations• Homogeneous and single phase material is best for identification of an

unknown• Requires tenths of a gram of material which must be ground into a powder• For mixed materials, detection limit is ~ 2% of sample• Peak overlay may occur and worsens for high angle 'reflections'• For unit cell determinations, indexing of patterns for non-isometric crystal

systems is complicated

LOGOSample Collection and PreparationDetermination of an unknown requires: the material, an instrument for grinding, and a sample holder.

• Obtain a few tenths of a gram (or more) of the material, as pure as possible• Grind the sample to a fine powder ~10 μm (or 200-mesh• Place into a sample holder or onto the sample surface:

• pack into a sample container• smear uniformly onto a glass slide, assuring a flat upper surface• sprinkle on double sticky tape

Typically the substrate is amorphous to avoid interference•For unit cell determinations, a small amount of a standard with known peak positions (that do not interfere with the sample) can be added and used to correct peak positions.

LOGOIII. Scanning Electron Microscope-SEM

 The scanning electron microscope (SEM) uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. 

Principles• The electron beam is accelerated through a high voltage

(20 kV) and pass through a system of apertures and electromagnetic lenses to produce a thin beam of electrons.

• Then the beam scans the surface of the specimen Electrons are emitted from the specimen by the action of the scanning beam and collected by a suitably- positioned detector.

LOGOIII. Scanning Electron Microscope-SEM

SEM consit of:1. Electron gun (Filament) 2. Condenser lenses3. Objective Aperture 4. Scan coils 5. Chamber (specimen test) 6. Detectors 7. Computer hardware and software

LOGOIII. Scanning Electron Microscope-SEM

These signals include:1. Secondary electrons (that produce

SEM images)2. Backscattered electrons (BSE)3. Diffracted backscattered electrons

(EBSD that are used to determine crystal structures and orientations of minerals)

4. Photons (characteristic X-rays that are used for elemental analysis and continuum X-rays)

5. Visible light (cathodoluminescence - CL), and heat.

LOGOApplication

The SEM is routinely used to generate high-resolution images of shapes of objects (SEI) and to show spatial variations in chemical compositions: 1) Acquiring elemental maps or spot chemical analyses using EDS2) Discrimination of phases based on mean atomic number

(commonly related to relative density) using BSE3) Compositional maps based on differences in trace element

"activitors" (typically transition metal and Rare Earth elements) using CL. 

The SEM is also widely used to identify phases based on qualitative chemical analysis and/or crystalline structure. Backescattered electron images (BSE) can be used for rapid discrimination of phases in multiphase samples. SEMs equipped with diffracted backscattered electron detectors (EBSD) can be used to examine microfabric and crystallographic orientation in many materials.

LOGOIII. Scanning Electron Microscope-SEM

Limitations1. Samples must be solid and fit into chamber.2. Maximum size 10cm length, 40mm diameter.3. Vacuum required 10-5 - 10-6 torr4. Required samples conductivity

LOGOIII. Scanning Electron Microscope-SEM

Sample Collection and Preparation Most electrically insulating samples are coated with a thin layer of conducting material (C, Au,…)The choice of material for conductive coatings depends on the data to be acquired: carbon is most desirable if elemental analysis is a priority, while metal coatings are most effective for high resolution electron imaging applications. Alternatively, an electrically insulating sample can be examined without a conductive coating in an instrument capable of "low vacuum" operation.

LOGOEnergy-dispersive X-ray spectroscopy - EDS

EDS is an analytical technique used for the elemental analysis or chemical characterization of a sample.

It relies on an interaction of some source of X-ray excitation and a sample When the electron beam is projected on the large energy solid, it

will penetrate deep into solid objects and atoms interact with electronic layers of atoms inside. This interaction leads to the creation of the X-rays characteristic wavelength is proportional to the atomic number (Z) of the atoms under Mosley's law:

The X-ray output frequency is featured with atoms of each substance present in the solids. And giving information abt element, composition of them.

LOGOIII. EXPERIMENTAL PROCEDURE

Fe + TiC(Ex-situ)

Milling

Powder Characterization

Compacting

Sintering

Ball/power ratio: 10/1Speed: 300 rpmTime: 5hMedium: n-hexane

Pressure: 300-500MPaBinder: Paraffin

BulkCharacterization

Fig. 3.2: Cycles heat

CharacterizationX-ray diffraction

SEM-EDXDensity

Hardness

Fig.3.1: Diagram of experimental procedure

Fe + Ti + C(In-situ)

CharacterizationX-ray diffraction

SEM-EDX

MillingBall/power ratio: 20/1Speed: 300 rpmTime: 10-15-20hMedium: n-hexane

Fig. 3.3: Phase diagram of Fe-TiC

LOGOIV. RESULTS AND DISCUSSION Characterization of raw materials

Power Fe Ti Graphite TiCSource China China Japan ChinaPurity ≥98% 99% 99.7% 99%

Particle size (μm) 35-75 35-75 5 2

Table 1: The specification of element powder in this study

Table 2: The chemical composition of powder mixture

Mixture: Fe + TiC (ex-situ)

Element Fe TiCwt.% 60 40

Mixture: Fe + Ti + C (in-situ)Element Fe Ti C

wt.% 60 32 8Fig. 4.1:XRD patterns of raw materials

LOGOIV. RESULTS AND DISCUSSION Structural evolution of as-milled

05/01/2023

Ti

TiC

Fig. 4.1: XRD pattern of as-milled powders after 10, 15 and 20 h of milling

In-situ process

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IV. RESULTS AND DISCUSSION Microstructure of as-milled

Fig. 4.2: Microstructures of as-milled powder after 20h of milling (a) 5000X, (b) 10000X.

Fig. 4.3: EDX of as-milled after 20 h of milling Fig.4.4: Elemental mapping of as-milled after 20 h of milling

-Uniform size distribution-Particle size: < 1μm

In-situ

Uniform distribution of elements in each particles

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05/01/2023

Fig. 4.5: XRD pattern of in-situ composite with milling time of 20h after sintering at 1250oC for 2h.

IV. RESULTS AND DISCUSSION XRD pattern of in-situ composite

-The absence of Ti peaks-The TiC peaks are more intense and well defined-The presences of some unexpected phases (TiO2 and FeTiO3)

The sample was not sintered in a good sintering atmosphere

LOGOAcronym Method Probe Signal Information Other Notes

OM Optical microscopy Light Light Surface microstructure

look at reflected or transmitted light

magnifications to 2000x

SEM Scanning electron microscopy

Beams of electron

Secondary electrons (SE)

Back-scattered electrons (BSE)

Characteristic X-rays

Light (cathodoluminescence) (CL)

Specimen current and transmitted electrons

Sample's surface topography and composition)

10x – more than 500,000x

Can achieve resolution better than 1 nanometer

Specimens can be observed in high vacuum, in low vacuum, in wet conditions and at a wide range of cryogenic or elevated temperatures

TEM Transmission electron microscopy

Focused beams of electron

Undeflected and deflected electrons that penetrate the sample thickness

Morphologic, compositional and crystallographic information on samples

Magnification up to 1000000x

Resolution below 1nm

XRD x-ray diffraction x-ray beam Diffraction pattern or 'diffractogram' Crystal surface Mineral species can be identified ("fingrprinted") even if only in very small particles

Mineralogical make up of sediments and sedimentary rocks can also be estimated (for species with concentrations in excess of about 5%)

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Case study: Fabricated Al MMC reinforced with nano-sized Al2O3

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SEM images of Al- Al2O3 particles before milling (0 hours) [M.S.Aboraia et al. (2013)]

The author observed the agglomerated Al2O3 particles. Agglomeration can be removed by increasing the milling time

LOGOSEM images of Al- Al2O3 powders 300 rpm after (a) 7h (b) 30h (c) 45h

(a) Flattened Al (b) Fragmented Al2O3 (C) Al particles spitted- Al2O3 cluster disappeared and homogeneously distributed

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XRD patterns of Al- Al2O3 powder milled for different times 7, 12, 15, 21, 30, 38 and 45 h

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(a) Aluminium particle (b) α-Al2O3 particle

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17 (a) Morphology and particle size distribution Fig.17 (b) of initial powder for Al-2024

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(c) Morphology and particle size distribution Fig.17 (d) of initial powder for FMG

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a) SEM morphology of 24h milled (b) cross section morphology of powder

Composite powder.

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(a) SEM images of nano Al2O3 powders, and (b) Al/ Al2O3 powders after 6h ball milling time.

LOGOReferrence Text book: The Basics of Crystallography and Diffraction, Third

Edition - Christopher Hammond http://

www.surfacesciencewestern.com/analytical-services/scanning-electron-microscopy-coupled-with-energy-dispersive-x-ray-semedx-spectroscopy/

http://serc.carleton.edu/research_education/geochemsheets/techniques/XRD.html

http://serc.carleton.edu/research_education/geochemsheets/techniques/SEM.html

SYNTHESIZING OF Fe-TiC COMPOSITE FROM Fe+Ti+C/Fe+TiC POWDERS BY POWDER METALLURGY METHOD- Trinh Van Ba

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www.themegallery.com

www.themegallery.com