M.Ing. / This report documents the steps taken to gain insight into the phenomena of high speed machining (HSM) of titanium alloys. This was done by firstly studying titanium alloys and the problems associated with machining titanium alloys. An experimental set-up and procedure was developed for measuring and recording both the machining temperature and component forces. A sufficient set of experimental data was collected through extensive experimentation. The cutting temperatures and component forces in HSM of Ti-6Al-4V were examined simultaneously. The cutting speed was found to be the most influential and limiting parameter on the machining temperature and component forces. A new approach for modeling the temperatures in HSM of titanium alloys was developed. Analytical predictions of the cutting temperatures were performed and used to evaluate the influence of a variation in the process parameters on the cutting temperature. The research provides insight for future work into the phenomena of HSM of titanium alloys . The results of the analytical model were found to be representative and comparable to the experimental data. It is however expected that the deviation between the predicted and measured result may be significantly reduced by changing the experimental approach. It is recommended that a complete set of experiments be done, using a new tool insert for every cut, thus removing the effect of possible tool wear on the experimental data obtained. In addition it is recommended that the iterative solution be improved through more in depth programming, considering the change in both the thermal and mechanical materials properties with a change in temperature. Ultimately the assumptions made in order to simplify the problem addressed in this report needs to be improved upon, in order to analyze data trends and even magnitudes to a greater degree of certainty.

No description available.

Ti-6Al-2Sn-4Zr-2Mo-0.1Si specimens were shaped by repeated cycles of heating (to 954 °C) and hammer or press forging followed by a solution anneal that varied from 968 to 998 °C. The coupons were originally extracted from billets forged below the beta trans us ( 1009 °C) and slow cooled to ambient temperature. Macroscopic and microstructural banding is observed in some forged and solution annealed coupons, that consists of regions of elongated primary alpha. More significant banding is observed subsequent to annealing at lower temperatures (968 °C), whereas much less microstructural banding is present after annealing at higher temperatures (998 °C). About the same level of banding is observed in hammer forged and press forged coupons. The observation of these bands is significant since they may lead to inhomogeneous mechanical properties. Specifically, at least some types of banding are reported to affect the high temperature creep properties of this alloy. The origin of these bands was therefore researched. Classically, banding in Ti-6242-0.1Si has been regarded as a result of adiabatic shear, chill zone formation or compositional inhomogeneity. High and low magnification metallography, electron microprobe analysis and microhardness tests were performed on forged and annealed specimens in this investigation. The composition inside the bands appears identical to that outside of the bands. The fraction of primary alpha is also found to be identical. The bands have higher microhardness. These results suggest that the bands are not related to composition gradients. The bands also do not appear to be a result of adiabatic shear or other localized deformation. The bands of this study appear to originate from the elongated primary alpha microstructure of the forged billet (from which test coupons were extracted). The deformation of the extracted coupon may be neither fully homogeneous nor sufficiently substantial and the coupon is only partly statically restored after a solution anneal. Areas not fully restored appear as "bands" with elongated primary alpha, that are remnant of the starting billet microstructure. Therefore, a source of banding in Ti-6242-0.1Si alloy, additional to the classic sources, is evident. This type of banding is likely removed by relatively high solution treatment temperatures and perhaps greater plastic deformation during forging. / Graduation date: 1992

The properties of titanium alloys are based on alloy compositions and microstructures that consist of mixtures of the two allotropic modifications of titanium, the low temperature α (hcp) and the high temperature β (bcc) phases. This thesis deals with the hot working behaviour of three commercial titanium alloy compositions designated IMI834, Ti17 and Ti5553 with a focus and detailed analysis of the Ti5553 alloy. These alloys represent the differing uses of titanium alloys in the aerospace industry. IMI834 is a near α alloy used in high temperature creep resistant applications as compressor discs and blades in aeroengines. Ti17 is a high strength alloy α+β used at intermediate temperatures in fan and compressor discs of aeroengines, while Ti5553 is a high strength-high toughness metastable β alloy used in the undercarriages of aircraft. The three alloys have widely differing β transus temperatures (related to α phase stability) and compositions. Titanium alloys are vacuum arc melted and thermomechanically processed. This process involves ingot breakdown in β (bcc) phase, and subsequent thermomechanical processing in two-phase α+β (hcp+bcc) region at temperatures that typically involve volume fractions of α in lath or plate form ranging from 15% to about 30%. The thermomechanical processing breaks down lath α to spheroidal particles, a process known as globularisation. Chapter I of this thesis reviews the current understanding of the hot working of titanium alloys and microstructure evolution during the hot working process. Chapter II summarises the main experimental techniques used: the hot compression test, and subsequent microstructure and microtexture analysis by scanning electron microscopy and related electron back scattered diffraction techniques (EBSD), transmission electron microscopy and related precession electron diffraction techniques (PED) for orientation imaging. The starting structure in the α+β domain of hot work is generally not a random distribution of the 12 variant Burgers Orientation Relationship (BOR) between the α and β phases, (11̅0)β || (0001)α and <111>β || <112̅0>α . A variety of morphologies and distributions ranging from the typical colony structures of near α and α+β alloys to the fine distributions of variants arranged in a triangular fashion are observed with specific growth directions and habit planes. Chapter III describes a quantitative evaluation of α distribution that are typical of some of the starting structures for the hot working conditions used in this thesis, specifically in the Ti5553 alloy. For this purpose, a Matlab based script has been developed to measure the spatially correlated misorientation distribution. It was found that experimental spatially correlated misorientation distribution varies significantly from a random frequency for both pair and triplet wise distribution of α laths. The analysis of these structures by established techniques of analysis of self-accommodated structures based on strain energy minimisation shows that the observed variant distribution arise from the residual strain energy accommodation of the semi-coherent α plates. The hot working process has been examined through hot compression tests of the 3 alloys at strain rates ranging from 10-3 s-1 to 10 s-1 over a temperature range designed to maintain constant volume fractions of the α and β phases during deformation ranging from about 30% α to a fully β structure. Since extensive prior work has been carried on the processing of titanium alloys, Chapter IV focuses on a comparative study of hot deformation behaviour of the three alloys with an emphasis on isolating microstructural and other effects. The macroscopic flow behaviour has been analysed in terms of conventional rate equations relating stress, strain, strain rate and temperature. The three alloys show very similar features in their stress-strain behaviour. β phase deformation exhibits yield points whose magnitude varies with strain rate and temperature. The flow stress curves are typical of materials undergoing dynamic recovery and recrystallization processes. The stress-strain behaviour in the α+β domain of hot work exhibits significant flow softening in the early stages of deformation with a subsequent approach to steady-state behaviour at true strain of about 0.5. Activation energy analysis of the steady state condition suggests that the rate controlling mechanism is related to recovery in the β phase in both α+β and β processing. Zener-Hollomon plots of the flow stress in the three alloys indicate that their flow stress can be normalized to a temperature-compensated strain rate and they differ only in the slopes of the plots that are related to the stress exponent. Empirical constitutive models were developed for a predictive understanding of the flow stress as a function of strain, strain rate and temperature using conventional rate equations for the flow stress Chapter V and VI examine the evolution of microstructure and microtexture in detail during hot deformation and subsequent heat treatment in Ti5553. A combination of EBSD (micron and submicron scale) and PED (nano meter scale) is used in orientation imaging to examine the globularisation process of the α phase and the recovery and recrystallization in the β phase in both supertransus and subtransus hot compression. The understanding of these processes is enhanced by tracking the same starting β grain through the deformation process. The effect of strain, strain rate and temperature on the evolution of subgrains in α and its fragmentation into spheroidal α is quantified. In the absence of shear bands, the globularisation process is seen to evolve from a strain driven Raleigh instability of the plate α, by subgrain formation in α and β phases. The related microtexture evolution is analysed. The analysis of recovery and microtexture evolution in the β phase described here has not been attempted earlier in the literature. The overall evolution of structure and texture is seen to result from the complex interplay between recovery and recrystallisation in the α and β phases in substranus deformation. While the Burgers orientation relationship between α and β is lost in the early stages of deformation, it appears to be restored at large strains as a consequence of ‘epitaxial’ recrystallisation processes that seem to result from the discontinuous nucleation of recrystallization of either phase at interphase interfaces in the Burgers orientation. The effect of substranus deformation on β texture following supertransus post deformation heat treatment is also examined and compared with β textures resulting from alternative strain paths such as friction stir processing. Finally Chapter VII summarises these results and the new insights into the evolution of structure and microtexture during hot deformation of titanium alloys and suggests directions for future work.

Titanium alloys are important engineering alloys that are extensively used in various industries. This is due to their unique combination of mechanical and physical properties such as low density combined with high strength and toughness as well as outstanding corrosion resistance. An additional benefit associated with Ti alloys, in general, is that their properties are relatively temperature-insensitive between cryogenic temperature and ~500 °C. Amongst the Ti alloys, Ti-6Al-4V (referred as Ti64) is a widely used alloy. Conventionally cast Ti64 possesses classical Widmanstätten microstructure of (hcp) α and (bcc) β phases. However this microstructure suffers from large prior β grain size, which tends be in the order of a few mm. Such large grain sizes are associated with poor processability as well as inferior mechanical performance. The necessity to break this coarse as-cast microstructure down, through several successive thermo-mechanical processing steps, adds considerably to the cost of finished Ti alloy products, making them expensive vis-à-vis other competing alloys. The addition of small amount of B (~0.1%) to Ti64 alloys, on the other hand reduces the cast grain size from couple of mm to ~200 µm. Moreover, addition of B to Ti alloys produces the intermetallic TiB needles during solidification by an in situ chemical reaction. The overall objective of this work is to gain insights into the role of microstructural modifications, induced by B addition to Ti64, on the mechanical performance of the alloys, in particular the room temperature damage tolerance (fracture toughness and fatigue crack growth) characteristics. The key questions we seek to answer through this study are the following: (a) What role does the microstructural refinement plays on the quasistatic as well as fracture and fatigue behavior and high temperature deformability of the alloys? (c) A hierarchy of microstructural length scales exist in Ti alloys. These are the lath, colony and grain sizes. Which of these microstructural parameters control the mechanical performance of the alloy? (b) What (possibly detrimental) role, if any, do the TiB needles play in influencing the mechanical performance of Ti64 alloys? This is because TiB being much stiffer, strain incompatibility between the matrix and the TiB phase could lead to easy nucleation of cracks during cyclic loading as well as can pose problems during dynamic deformation. (d) What is the optimum amount of B that can be added to Ti64 such that the most desirable combination of properties can be achieved? Five B-modified Ti64 alloys with B content varying from 0.0 to 0.55 wt.% were utilised to answer the above questions. Marked prior β grain size reduction was noted with up to 0.1 wt.% B addition. Simultaneous refinement of α/β colony size has also been observed. The addition of B to Ti64, on the other hand increases the α lath size. The TiB needles that form in-situ during casting are arranged in a necklace like structure surrounding the grain boundaries for higher B added Ti64 alloys. An anomalous enhancement in elastic modulus, E, of the alloy with only 0.04 wt.% B to Ti64 was found. E has been found to follow the same trend of variation with B content at higher temperatures (up to 600 °C) as well. Nanoindentation experiments were conducted to evaluate the moduli of the various phases present in the microstructure and then rationalize the experimental trends within the framework of approximate models. Marginal but continuous enhancement in strength of the alloys with B addition was observed. It correlates well with the grain size refinement according to Hall-Petch relationship. Ductility on the other hand increases initially with up to 0.1 wt.% B addition followed by a reduction. While the former is due to the microstructural refinement, the latter is due to the presence of significant amount of brittle TiB phase. Room temperature fracture toughness decreases with B addition to Ti64. Such reduction in fracture toughness with the refinement of prior β grain size has been justified with Ritchie-Knott-Rice model. Contradictory roles of microstructural refinement have been observed for notched and un-notched fatigue. While reduction in length scale has a negative role in crack propagation, it enhances the fatigue strength of the alloy owing to better resistance to fatigue crack initiation. TiB needles on the other hand act as sites for crack initiation and hence limit the enhancement in fatigue strength of alloys with 0.30 and 0.55 wt.% B. An investigation of the high temperature deformability of the alloys has been performed over a wide range of temperature (within the two phase α+β regime) and strain rate windows. Results show that microstructural refinement does not alter the high temperature deformation characteristics as well as optimum processing conditions of the alloys. TiB needles, however act as sites for instability owing to differences in compressibility between the matrix and the whisker phase. In summary, this study suggests that the addition of ~0.1 wt.% B to Ti64 can lead to the elimination of certain thermo-mechanical processing steps that are otherwise necessary for breaking the as-cast structure down and hence make finished Ti components more affordable. In addition, it leads to marginal enhancement in the quasi-static properties and significant benefits in terms of high cycle fatigue performance.

published_or_final_version / Dentistry / Master / Master of Dental Surgery

A thesis submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering Johannesburg, 2016 / The thesis investigated the effect of partial substitution of Cr or Ti with 2-6 at.% Fe, or 0.05-0.10 at.% Rh/Pd on the structure, hardness, corrosion behaviour and hydrogen storage characteristics of an arc-melted Ti35V40Cr25 at.% alloy. The effects of an annealing and a quenching heat treatment on the properties were also investigated. Melting of the eight alloys was done in a water-cooled, copper-hearth arc melting furnace under an argon atmosphere. Each of the eight ingots was cut into three: one as the as-cast sample and the other two separately quartz-sealed and loaded in two batches in a heat treatment oven and heated to 1000 °C for 1 hour. The first set of quartz tubes were immediately removed and broken in cold water to quench the alloy, hence locking the microstructure. The second batch was loaded into the furnace, heated to 1000 °C for 1 hour and then slowly furnace-cooled. The alloys (as-cast and heat treated) were characterised for phase identification using optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) with Electron Diffraction X-ray Spectroscopy (EDS) using an Oxford system. Thermo-Calc software was used to model the phases using the Solid Solution 4 and Titanium 3 Databases. The hardness values (under a 2 kg load) of all samples were recorded. Potentiodynamic corrosion tests were performed in 6M KOH at 25 °C, and Tafel curves were recorded from -1.4V to -0.2V with a scanning rate of 1mV/sec. A Sievert’s apparatus was used for pressure composition temperature (PCT) measurements at 30, 60 and 90 °C. All the alloys contained a primary bcc (V) phase. The secondary phases were a combination of αTi, Ti(Cr,V)2 Laves phases (C14, C15 or C36) and a minor ωTi phase. The cell volume of the primary (V) phase decreased with addition of Fe and 0.05 Rh but increased with 0.1 Rh and Pd. The hardness of the base alloy increased with additions of Fe and 0.10 at.% Pd, but decreased with additions of Rh and 0.05 at.% Pd. Additions of Rh, Pd and 2 at.% Fe decreased the corrosion rate, while additions of 5 and 6 at.% Fe increased the corrosion rate. The reversible hydrogen storage capacity (RHSC) of the base alloy, otherwise known as useful capacity, was enhanced with addition of Pd and Rh, but decreased with Fe addition. Both annealing and quenching increased the hardness of the 0.05 at.% Rh and all the Fe containing alloys. Heat treatment decreased the hardness of the base alloy, both Pd alloys and v the 0.10 at.% Rh samples. Quenching decreased the hardness of the 0.10 at.% Rh and both Pd-containing alloys. The corrosion rate of the 0, 5 and 6 at.% Fe, 0.05 at.% Rh and the Pd-containing alloys decreased after annealing.at.% FeThe rate increased after annealing the 2 at.% Fe and 0.10 at,% Rh samples. The as-cast sample containing 2 at.% Fe had the lowest corrosion rate (0.0004 mm/y) and the quenched 6 at.% Fe was the least corrosion resistant sample with a corrosion rate of 0.037 mm/y. The quenched 5% Fe alloy had the highest hardness (460 MPa), while the annealed 0.10 at.% Rh sample had the lowest (388 MPa). The quenched 0.05 at.% Pd sample had the highest RHSC (2.28 wt%) while the lowest RHSC of 0.44 wt% was observed in the as-cast 2 at.% Fe sample. Annealing improved the RHSC of all samples except the base Ti35V40Cr25 and 6 at.% Fe alloys, while quenching was detrimental to RHSC of all the samples but the 2 at.% Fe, 0.05 at.% Pd and 0.10 at.% Rh alloys. Increasing the addition of palladium from 0.05 to 0.10 at.% Pd showed no significant improvement on RHSC of the base alloy, thus addition of 0.05 at.% Pd would be sufficient. The RHSC of the annealed 0.05 Rh alloy (2.25 wt% H) was close to the value of the 0.10 at.% Pd, so rhodium could be considered as an alternative to the quenched 0.05 at.% Pd. The RHSC was 1.56, 0.44, 0.75 and 0.68 wt% for 0, 2, 5 and 6 at.% Fe as-cast alloys respectively. Although the 2 at.% Fe alloy had the lowest RHSC, it could find its application as electrode in 6M KOH solution electrolyte because of its low corrosion rate. / MT2016

Ka-fai Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Ka-fai Ho. / Acknowledgments --- p.i / Abstract --- p.ii / 摘要 --- p.iv / Figures Captions --- p.v / Tables Captions --- p.xii / Table of contents --- p.xiii / Chapter Chapter one --- Introduction --- p.1-1 / Chapter 1.1 --- Metal Matrix Composite --- p.1-1 / Chapter 1.1.1 --- Matrix Materials --- p.1-2 / Chapter 1.1.1.1 --- Aluminum --- p.1-2 / Chapter 1.1.1.2 --- Titanium --- p.1-3 / Chapter 1.1.2 --- Type of reinforcements --- p.1-3 / Chapter 1.2 --- Conventional Fabrication method --- p.1-4 / Chapter 1.2.1 --- Liquid Phase processing --- p.1-4 / Chapter 1.2.1.1 --- Slurry deposition --- p.1-4 / Chapter 1.2.1.2 --- Squeeze casing (Pressure infiltration) --- p.1-4 / Chapter 1.2.2 --- Solid Phase processing --- p.1-5 / Chapter 1.2.2.1 --- Diffusion bonding --- p.1-5 / Chapter 1.2.2.2 --- Powder Metallurgy (P/M) --- p.1-5 / Chapter 1.2.3 --- In-situ processing --- p.1-7 / Chapter 1.3 --- Sintering processing --- p.1-7 / Chapter 1.3.1 --- Pore structure --- p.1-8 / Chapter 1.3.2 --- Compression effect on sintering --- p.1-9 / References / Chapter Chapter Two --- Methodology and Instrumentation --- p.2-1 / Chapter 2.1 --- Al-Ti-C composites --- p.2-1 / Chapter 2.1.1 --- Introduction --- p.2-1 / Chapter 2.1.2 --- Aim and Motivation --- p.2-2 / Chapter 2.1.2.1 --- Compositions and Fabrications --- p.2-2 / Chapter 2.1.2.2 --- Testing --- p.2-3 / Chapter 2.1.3 --- The Flow of the Thesis --- p.2-3 / Chapter 2.2 --- Instrumentation --- p.2-4 / Chapter 2.2.1 --- Ball-milling machine --- p.2-4 / Chapter 2.2.2 --- High temperature furnace --- p.2-5 / Chapter 2.2.3 --- Arc-melting furnace --- p.2-5 / Chapter 2.2.4 --- Instron loading machine --- p.2-6 / Chapter 2.2.5 --- Density measurement --- p.2-6 / Chapter 2.2.6 --- Vickers' Hardness Tester --- p.2-8 / Chapter 2.2.7 --- X-ray diffraction analysis --- p.2-8 / Chapter 2.2.8 --- Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDXS) --- p.2-9 / References / Chapter Chapter Three --- Fabrication of Al-16Ti-C composites by Powder Metallurgy method --- p.3-1 / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.2 --- Experiments --- p.3-1 / Chapter 3.2.1 --- Experiments on Pressing pressure --- p.3-1 / Chapter 3.2.2 --- Firing temperature and duration time --- p.3-2 / Chapter 3.3 --- Results --- p.3-2 / Chapter 3.3.1 --- Pressing pressure --- p.3-2 / Chapter 3.3.1.1 --- Relative Density --- p.3-2 / Chapter 3.3.1.2 --- Surface Porosity --- p.3-2 / Chapter 3.3.1.3 --- Microhardness --- p.3-3 / Chapter 3.3.1.4 --- X-ray diffraction analysis --- p.3-3 / Chapter 3.3.1.5 --- Microstructure --- p.3-3 / Chapter 3.3.2 --- Firing temperature and duration time --- p.3-4 / Chapter 3.3.2.1 --- Microhardness --- p.3-4 / Chapter 3.3.2.2 --- X-ray diffraction analysis --- p.3-4 / Chapter 3.3.2.3 --- Microstructure --- p.3-4 / Chapter 3.4 --- Discussion --- p.3-5 / Chapter 3.4.1 --- Pressing pressure --- p.3.5 / Chapter 3.4.2 --- Firing temperature and time duration --- p.3-6 / Chapter 3.5 --- Conclusions --- p.3-6 / References / Chapter Chapter Four --- Effects of the size of Aluminum powder on the properties of Al-16Ti-4C composites --- p.4-1 / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Experiments --- p.4-1 / Chapter 4.3 --- Results --- p.4-2 / Chapter 4.3.1 --- Relative density --- p.4-2 / Chapter 4.3.2 --- Microhardness --- p.4-3 / Chapter 4.3.3 --- Fracture Strength --- p.4-3 / Chapter 4.3.4 --- X-ray diffraction analysis --- p.4-3 / Chapter 4.3.5 --- Microstructure --- p.4-4 / Chapter 4.3.5.1 --- Microstructure of the surface --- p.4-4 / Chapter 4.3.5.2 --- Microstructure of the fracture surface --- p.4-4 / Chapter 4.4 --- Discussion --- p.4-5 / Chapter 4.4.1 --- Sintering procedure --- p.4-5 / Chapter 4.4.2 --- Fracture model --- p.4-6 / Chapter 4.4.3 --- X-ray diffraction analysis --- p.4-6 / Chapter 4.5 --- Conclusions --- p.4-7 / References / Chapter Chapter Five --- Effects of different sintering temperature on the properties of Al-16Ti-4C composites --- p.5-1 / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Experiments --- p.5-1 / Chapter 5.3 --- Results --- p.5-2 / Chapter 5.3.1 --- Relative density --- p.5-2 / Chapter 5.3.2 --- Microhardness --- p.5-2 / Chapter 5.3.3 --- Fracture Strength --- p.5-2 / Chapter 5.3.4 --- X-ray diffraction analysis --- p.5-2 / Chapter 5.3.5 --- Microstructure --- p.5-3 / Chapter 5.3.5.1 --- Surface microstructure --- p.5-3 / Chapter 5.3.5.2 --- Fracture surface microstructure --- p.5-3 / Chapter 5.4 --- Discussion --- p.5-3 / Chapter 5.4.1 --- Sintering procedure and microstructure --- p.5-3 / Chapter 5.4.2 --- Hardness and fracture strength --- p.5-4 / Chapter 5.4.3 --- Model of fracture --- p.5-5 / Chapter 5.5 --- Conclusions --- p.5-5 / Chapter Chapter Six --- Fabrication of TiC by Arc melting method --- p.6-1 / Chapter 6.1 --- Introduction --- p.6-1 / Chapter 6.2 --- Experiments --- p.6-2 / Chapter 6.3 --- Results --- p.6-2 / Chapter 6.3.1 --- X-ray diffraction analysis --- p.6-2 / Chapter 6.3.2 --- Microstructure --- p.6-2 / Chapter 6.4 --- Discussion --- p.6-2 / Chapter 6.4.1 --- Composition --- p.6-2 / Chapter 6.4.2 --- Sintering process --- p.6-3 / Chapter 6.5 --- Conclusions --- p.6-3 / References / Chapter Chapter Seven --- The Effects of the contents of Ti and C on the properties of Al-TiC and Al-Ti-C composites --- p.7-1 / Chapter 7.1 --- Introduction --- p.7-1 / Chapter 7.2 --- Experiments --- p.7-1 / Chapter 7.3 --- Results --- p.7-2 / Chapter 7.3.1 --- Relative density --- p.7-2 / Chapter 7.3.2 --- Microhardness --- p.7-2 / Chapter 7.3.3 --- Fracture Strength --- p.7-2 / Chapter 7.3.4 --- X-ray diffraction analysis --- p.7-3 / Chapter 7.3.5 --- Microstructure --- p.7-3 / Chapter 7.3.5.1 --- Surface microstructure --- p.7-3 / Chapter 7.3.5.2 --- Fracture surface microstructure --- p.7-4 / Chapter 7.4 --- Discussion --- p.7-4 / Chapter 7.4.1 --- Hardening effect --- p.7-4 / Chapter 7.4.2 --- Relationship between fracture strength and relative density --- p.7-4 / Chapter 7.4.3 --- Fracture model --- p.7-5 / Chapter 7.5 --- Conclusions --- p.7-5 / References / Chapter Chapter Eight --- Conclusions and Future Work --- p.8-1 / Chapter 8.1 --- Summary --- p.8-1 / Chapter 8.2 --- Future Work --- p.8-2 / References

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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by R. Sheldon Carpenter. / B.S.