MATL913/MATE413 SEM report 2Ternary phase diagram of a Ti-42Al-10Mn alloy at 1000C1. Material and...

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MATL913/MATE413 SEM report 2Ternary phase diagram of a Ti-42Al-10Mn alloy at 1000C1. Material and heat treatmentThe nominal composition and the chemical analysis of the material are shown in table 1. A small piece of the material about 20mm x 10 mm x 5 mm was encapsulated in a quartz tube in vacuum. The encapsulated sample was placed in a tube furnace at 1350C for 2h then water quenched to room temperature and it was placed a tube furnace at 1000C and held there for 168 h (a week) then water quenched to room temperature.    Alloy    Nominal composition (at. %)    Chemical analysis (at. %)                                Ti-42Al-10Mn    48    42    10    47.6    43.0    9.42. SEM sample preparationA thin slice (5 mm thick) of the heat-treated sample was mounted in conductive Bakelite. The mounted sample was firstly ground with wet and dry paper up to #1200 and then polished with 1 m diamond paste. The final polish was accomplished with TiO2 colloidal suspension assisted with drops of 1%HF acid. The sample surface has a mior finish without any visible scratches and ready for SEM observation. 3. SEM operation conditionsa. Instrument: JCM-6000 . Operations: Working distance of 15 mm at 15 kV. Secondary electron and backscattered electron imaging modes were used for the microstructure observation. Backscattered electron images were recorded. Large area EDS analysis as well as spot analyses of individual phases were caied out.4. Results (supplied separately)a. EDS of Ti-42Al-10Mn (Appendix 1). comparison of two analysis of the ight phase (α) (Appendix 2)(experimental and results descriptions: 30%)5. DiscussionsThe following questions should be addressed in the report 2a. Why the SEM sample used I this experiment was polished without etching? (5%). Why 15 mm working distance was chosen for the EDS work? (5%)c. The images supplied in this work are backscattered electron images and discuss the advantages of using backscattered electrons over the use of secondary electrons in this case. (10%)d. If secondary electrons were used for imaging what would you expect the differences between the backscattered electron images and the would-be secondary electron images? (5%)e. Why do we need to have an area analysis before the spot analysis? (5%)f. In the EDS microanalysis a standardless program was used to cover x-ray intensities into compositions. Explain what does the standardless analysis mean?  Discuss the advantage and disadvantage of using standardless EDS program to analyze the composition of a material. (35%)g. Usually several analysis points of the same phase are chosen. It is normal if there is a small discrepancy between analysis points of the same phase. However, the difference shown in two points of the same ight α phase is too large to be normal. Discuss the possible reasons for the abnormal observation. (5%)h. Plot the composition of the alloy and the compositions of α(ight),(grey) and  (dark matrix)in an equilateral triangle and connect the compositions of α(ight),(grey) and  (dark matrix) to form a triangle known as tie-triangle i.e. a part of a ternary phase diagram at 1000C. Is the composition of the alloy within the triangle? (5%)i. Use the tie-triangle and the lever rule to work out the volume fraction of each phases in the system. (5%)j. You may work out the volume fraction of each phase from the backscattered image using Image J (Image J software can be download free from https:imagej.nih.gov/ij/ . User guide is available at https:imagej.nih.gov/ij/docs/index.html) (bonus) (10%)Appendix 1ZAF Method Standardless Quantitative AnalysisFitting Coefficient : 0.0754Element XXXXXXXXXXkeV)   Mass%   Sigma   Atom%  Compound   Mass%  Cation XXXXXXXXXXKAl K XXXXXXXXXX XXXXXXXXXX05          XXXXXXXXXX19.4161Ti K XXXXXXXXXX XXXXXXXXXX33          XXXXXXXXXX67.8494Mn K XXXXXXXXXX XXXXXXXXXX61          XXXXXXXXXX12.7345Total XXXXXXXXXX XXXXXXXXXX                          Acquisition ParameteInstrument   : JCM-6000Acc. Voltage : 15.0 kVProbe Cuent: XXXXXXXXXXnAPHA mode     : T2Real Time    : 52.43 secLive Time    : 50.00 secDead Time    : 4 %Counting Rate: 8180 cpsEnergy Range : XXXXXXXXXXkeVTitle        : BF---------------------------Instrument   : JCM-6000Volt         : 15.00 kVMag.         : x 1,000Date         : 2019/03/28Pixel        : 1024 x 768Area analysisJEOL  1/1ZAF Method Standardless Quantitative AnalysisFitting Coefficient : 0.0812Element XXXXXXXXXXkeV)   Mass%   Sigma   Atom%  Compound   Mass%  Cation XXXXXXXXXXKAl K XXXXXXXXXX XXXXXXXXXX87          XXXXXXXXXX11.1176Ti K XXXXXXXXXX XXXXXXXXXX46          XXXXXXXXXX48.1894Mn K XXXXXXXXXX XXXXXXXXXX67          XXXXXXXXXX40.6930Total XXXXXXXXXX XXXXXXXXXX                          Acquisition ParameteInstrument   : JCM-6000Acc. Voltage : 15.0 kVProbe Cuent: XXXXXXXXXXnAPHA mode     : T2Real Time    : 52.10 secLive Time    : 50.00 secDead Time    : 4 %Counting Rate: 6967 cpsEnergy Range : XXXXXXXXXXkeVTitle        : BF---------------------------Instrument   : JCM-6000Volt         : 15.00 kVMag.         : x 1,000Date         : 2019/03/28Pixel        : 1024 x 768Bright phase (α) analysisJEOL  1/1ZAF Method Standardless Quantitative AnalysisFitting Coefficient : 0.0707Element XXXXXXXXXXkeV)   Mass%   Sigma   Atom%  Compound   Mass%  Cation XXXXXXXXXXKAl K XXXXXXXXXX XXXXXXXXXX04          XXXXXXXXXX17.3716Ti K XXXXXXXXXX XXXXXXXXXX10          XXXXXXXXXX71.4183Mn K XXXXXXXXXX XXXXXXXXXX87          XXXXXXXXXX11.2100Total XXXXXXXXXX XXXXXXXXXX                          Acquisition ParameteInstrument   : JCM-6000Acc. Voltage : 15.0 kVProbe Cuent: XXXXXXXXXXnAPHA mode     : T2Real Time    : 52.28 secLive Time    : 50.00 secDead Time    : 4 %Counting Rate: 7529 cpsEnergy Range : XXXXXXXXXXkeVTitle        : BF---------------------------Instrument   : JCM-6000Volt         : 15.00 kVMag.         : x 1,000Date         : 2019/03/28Pixel        : 1024 x 768Grey phase () analysis (004)JEOL  1/1ZAF Method Standardless Quantitative AnalysisFitting Coefficient : 0.0651Element XXXXXXXXXXkeV)   Mass%   Sigma   Atom%  Compound   Mass%  Cation XXXXXXXXXXKAl K XXXXXXXXXX XXXXXXXXXX51          XXXXXXXXXX22.5125Ti K XXXXXXXXXX XXXXXXXXXX

Rahul · Accepted Answer

Ternary phase diagram of a Ti-42Al-10Mn alloy at 1000°C
Module code: MATL913/MATE413
Submitted in partial fulfilment of the requirement for SEM Report at 
……………………..
By
………………….
May 2020
Table of contents
             Abstract
1. Problem statement…………………………………………………….. IV
2. Introduction……………………………………………………………….. IV
3. Discussions…………………………………………………………………..V
4. Results and discussion…………………………………………………XIII
5. References………………………………………………………………….XIV
6. Appendix 1………………………………………………………………….XV
7. Appendix 2………………………………………………………………….XIX
ABSTRACT
The material TI-42 Al-10 Mn is heat treated, polished, and prepared for SEM (Scanning electron Microscopy) observation. Secondary and backscattered electrons are used to form an image. The Area analysis is used to find the composition of the sample. The obtained image is analysed using standardless analysis which gives the composition without standardization of elements. The spot analysis is performed to find the phases of elements and see the composition on that particular spot. The volumetric analysis is performed using Image J software to find the volume distribution. 
This paper discusses on the preparation of the sample for SEM analysis and placing of the sample in the machine JCM-6000, Discussions on Secondary and backscattered electron images standardless analysis, its advantages and disadvantages, Ternary phase diagrams are plotted for each of the EDM result present in Appendix 1 and volume fraction using lever rule and Image J software. 
1. Introduction
SEM (Scanning Electron Microscope) is a device that uses electron beams to produce a high resolution used to evaluate material surface, flaws, crystal structure, phases, contamination, and corrosion. The detailed internal structure is shown in fig 1.
Fig 1. Scanning Electron Microscope
The whole process of the experiment is mentioned in the below flowchart
1
Material of 20mm*10mm*5mm was encapulated in quartz tube vaccum
2
Heat treatment -heating at 1350°C  for 2h then water quenched to room temperature
kept in tube furnace at 1000°C  for 168h then quenched to room temperature
3.
5mm thick slice is mounted in Bakelite and grinded with wet and dry paper upto #1200 
Then polished with 1μm Diamond paste
Finally polished with Ti and assisted with 1%HF acid
4.
The JCM machine is used to phases using Secondary electron and backscattering electron modes.
5.
The standardless analysis is done to predict the composition.
The Backscattered images are produced to analyze further for volumetric fraction
2. Discussions
a) Why is the SEM sample used in this experiment polished without etching? 
· This answer mainly depends on what we want to deserve and how the specimen is mounted.  Sample preparations are essential in scanning electron microscopy. Flawed sample preparations can undetermine the quality of results and lead to false conclusions.  If we are observing flat polished microstructure.  Then polishing itself is sufficient then there is no need of ething.  The SEM has to be etched very little but etching can lead to varying the EDS results. It changes the results especially when we are observing all the phases and some small features.
b) Why 15 mm working distance was chosen for the EDS work? 
WD in the data bar of an SEM micrograph is the focal length of the objective lens.       The physical working distance is the distance between the objective lens and the sample. The image is focused when the focal length of the objective lens equals the physical working distance. SEM manufacturers always abbreviate focal length of the objective lens as working distance because they assume users want to be in focus.
· 
Fig 2. Working distance in SEM
If you don't know the correct WD for EDS do the following: Collect a spectrum while moving the Z-stage. To be safe, start with a short WD (8mm) and move down. Observe the count rate. When the count rate is at the maximum, you have found the correct WD for EDS. Many EDS detectors have slit shaped collimators, so it is possible to be near the max count rate over a range of working distances. It is probably smart to refocus every mm or so, although in theory, this should not make much difference. For most conventional SEMs with a standard pin hole type objective lens, EDS working distances are typically 15 mm.
c) The images supplied in this work are backscattered electron images and discuss the advantages of using backscattered electrons over the use of secondary electrons in this case. (10%)
· Backscattered electrons are reflected back after elastic interactions between the beam and the sample. Secondary electrons, however, originate from the atoms of the sample: they are a result of inelastic interactions between the electron beam and the sample
· When the electron beam strikes the surface of the specimen the various radiation is observed among which one is Backscattered electrons. These are detected by detectors and convert them into electrical signals. The signal is proportional to the atomic structure of the sample volume.
 
Fig 3.

MATL913/MATE413 SEM report 2 Ternary phase diagram of a Ti-42Al-10Mn alloy at 1000C 1. Material and heat treatment The nominal composition and the chemical analysis of the material are shown in table...

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