Metal played important role in the social and economic development of societies since its discovery. It is so important that the some part of humankind historical development were designated by the type of metal which was extensively used depending upon the level of technology of that period enabling the processing of metal like bronze age and iron age. In this frame, the rich metal deposits of Anatolia made this region a very important metal working and civilization center. K&uuml / ltepe where it was the center of the trade organization in Anatolia realized between Assur and Anatolia during 1945-1730 B.C called Assyrian Trade Colonies Period was one of the most important metal working center of Anatolia at that period. In this thesis, it is aimed to make a contribution to understand the metal working technology in K&uuml / ltepe by examining the uncovered metal artifacts dated to that period. For this purpose, the metal artifacts uncovered from K&uuml / ltepe Ancient Site belonging to Colonies Period which are exhibited in the Anatolian Civilization Museum were examined by portable XRF (PXRF) to obtain the quantity of elements that constituted the artifacts without giving any harm to the artifact. Besides the examination of exhibited artifacts in the Anatolian Civilization Museum, the uncovered metal artifact parts belonging to Colonies Period which are not suitable for exhibition and separated for studying were examined by energy dispersive X-ray unit of scanning electron microscope for elemental analysis and by X-ray diffraction for the analysis of minerals. The microstructures of artifacts were examined by scanning electron microscope and optical microscope for revealing the operations on metal applied by ancient metalsmith. In addition to analysis mentioned above, in order to make a contribution to understand the copper trade between K&uuml / ltepe and its environs lead isotope analysis of some samples from the separated metal artifacts for studying was also performed. As a result of all those analyses, it was concluded that K&uuml / ltepe ancient metalsmiths in Colonies Period had the knowledge to smelt the copper and to pour molten metal into a mold to produce an object of desired shape. Moreover, they also discovered that the addition of some elements to copper hardens the structure. In this frame the bronze to be obtained by deliberately adding of tin to copper was attained. In addition, they were aware of shaping the casted object by hammering. In the meantime, they had the knowledge of heat treatment that allows them forging the object many times till giving the desired shape without causing the fracture in the structure.

Understanding the asymmetry in core collapse supernova explosions is pointed out by various astrophysicists as it is the key factor in determining the observational properties of the pulsars. The initial kick given by the ex- plosion to the pulsar affects its spin period and space velocity. Up to now, although the observations do not show a direct relation between the observational features of the pulsar and its space velocity, they show a clear relation between the spin period and the magnetic field strength, hence its radiation processes. In this thesis, as the method, tracing the companions of progenitors if they were in close binaries, which becomes a runaway star after the supernova explosion was chosen. Over the candidates selected in Guseinov et al (2005), the spectral types of 11 runaway candidates from 7 supernova remnants determined through analyzing their spectroscopic observations. Radial velocity determination was applied to the discovered B6V type star GSC 03156-01430 inside the supernova remnant G78.2+2.1. Also by studying the proper motion data, we compared the motion of the runaway star and the related pulsar in order to determine the asymmetry in the supernova explosion. The neutron star PSR 2021+4026 is moving with a 2-D velocity of &sim / 580 km/s with respect to the rest frame of its birth association Cyg OB9. &sim / 550 km/s more than expected in the symmetric case. Re-constructing the pre-supernova binary shows that the asymmetry in the supernova explosion does not depend on the binarity.

Martensite-to-Beta transformation temperatures of CuAlNiMn and CuAlNi shape memory alloys has been determined by differential scanning calorimetry (DSC). In CuAlNiMn alloys, each new betatizing treatment has resulted in randomly varying transformation temperatures on the same specimen and an anomalously diffuse and serrated Martensite-to-Beta transformation peaks in the first cycle. Therefore, as quenched alloy samples were thermally cycled for three times in DSC prior to ageing to obtain thermally stable and reproducible transformation temperatures and to eliminate the anomalous effect of betatizing on the transformation temperatures. CuAlNiMn alloys were aged in martensitic condition at temperatures in the range 80&amp / #61616 / C to 150&amp / #61616 / C for 24 hours to 312 hours ageing periods. Both A_s and A_f temperatures have increased with ageing temperature and time while M_s and M_f temperatures have not changed during martensite ageing. Transformation temperatures of CuAlNi alloys, on the other hand, have not changed during martensite ageing. In this respect, CuAlNiMn alloys were found to be more prone to martensite stabilization than the CuAlNi alloys. Through Transmission Electron Microscope investigation in the Cu-12.6wt%Al-5.9wt%Ni-1.8wt%Mn alloy aged at 150&amp / #61616 / C for 312 hours has revealed no sign of precipitate formation and it has been concluded that the &amp / #65533 / precipitates pinning martensite boundaries&amp / #65533 / mechanism could not be responsible of martensite stabilization. Beta phase ageing of CuAlNiMn alloys at temperatures 200&amp / #61616 / C, 230&amp / #61616 / C, 250&amp / #61616 / C and 270&amp / #61616 / C, have drastically shortened the periods for stabilization to the extent that &amp / #946 / -to-M transformation completely ceases. With regard to the Manganese content, highest Manganese bearing alloy was the one stabilized first and the lowest manganese containing one was the longest lasting alloy during beta phase ageing. Beta stabilization was not observed in any of the four CuAlNi alloys at the end of 96 hours ageing at 200&amp / #61616 / C while beta stabilization was realized after 26, 38 and 11 hours ageing at the same temperature in the three Mn containing alloys studied. In conclusion, on the basis of ageing studies at 200&amp / #61616 / C, with regard to beta stabilization, CuAlNi alloys were found to be more resistant to high temperature ageing than CuAlNiMn alloys. Equilibrium &amp / #947 / _2 and &amp / #945 / phases were observed with coupled-grown lamellar morphologies in Cu-13.6%Al-3.0%Ni alloy aged above 400&amp / #61616 / C.

A study is carried out into fracture behavior of steel/steel laminates both experimentally and through finite element analysis (FEM). The laminates produced by hot pressing consisted of low carbon and medium carbon steels with two volume fractions / 0.41 and 0.81. Fracture toughness, JIC has been measured using partial unloading technique assuming a critical value of crack extension. The technique is initially applied to monolithic material and then to the laminates in crack divider orientation. Evaluation of fracture toughness of laminates indicates that there is a substantial improvement of JIC with increase in the volume fraction. The systems under study were also evaluated by FEM modeling with the use MARC package program. To evaluate JIC, the problem has been evaluated in several steps / first two-dimensional plane strain problem is considered. This is followed by three-dimensional case and then by an artificially layered system, all for monolithic materials. Values of JIC derived were close to one another in all cases. Following this verification, the method, as implemented in layered monolithic system, was applied to laminates. This has shown that JIC of laminates can be predicted using FEM analysis, including the delamination. Values of JIC varied in the same manner as the experiment verifying that fracture toughness in the current system increases with increase in volume fraction. It has been concluded that modeling as implemented in this work can be used for useful composite systems incorporating hard/brittle reinforcements both in crack divider and crack arrester orientation.

In the present work, the effect of variation in specimen orientation and heat treatment on the Stress Corrosion Cracking (SCC) susceptibility of 7050 aluminum alloy was investigated in 3,5% NaCl solution and under freely corroding conditions. For this purpose, Constant Extension Rate Tests (CERT) was performed on precracked Compact Tension (CT) specimens and the Direct Current Potential Drop technique was applied to measure the crack lengths. In addition to crack length versus time curves, the relationship between the crack growth rate and the stress intensity factor was determined. Fractographic analysis was utilized extensively to support the findings related with basic mechanisms of cracking. The alloy was found to be in the most susceptible state in the SL orientation, in which the crack propagation direction is parallel to the rolling direction. The resistance to SCC is higher in the TS but at maximum in LT orientation where the loading direction is parallel to the rolling direction. In the peak aging treatment, T651, alloy is susceptible to SCC in SL orientation. When the over aging treatment, T7651, is applied the resistance is increased and the two step over aging treatment, T73651, has resulted in an additional improvement in this orientation. On the other hand, the alloy showed higher resistance to SCC in TS and LT orientations in T651 condition compared to the T7651 and T73651 treatments. In these orientations, the alloy is less susceptible in T73651 condition than in T7651 treatment.

Material selection is one of the major points that should be taken into account seriously in the engineering design stage. Each material has various properties such as mechanical, thermal, electrical, physical, environmental, optical and biological properties. However, it is a well known fact that only a limited number of design engineers have a thorough knowledge on all these properties of a specific material, which is planned to be used in the manufacturing of the product. Therefore, the design engineer should be guided in selecting the most suitable material. In the scope of this thesis, the aim was to develop an algorithm and a software package for material selection to help the design engineer in his decision making process. In the program, since steel is a widely used material in industry, it was selected as a material class among whole engineering materials, and a database covering all the necessary properties of various steels was constructed. These properties include chemical, mechanical, thermal, electrical and physical properties for steels. The database developed by using Microsoft Access also contains steels of 29 different steel standards and can be updated if the user wants. The software package was developed for Windows environment by using Microsoft Visual Basic 6.0. In the program, steels can be searched for the list of suitable steels by entering application areas and properties such as chemical component, yield strength, heat capacity and electrical resistance. In addition to this, lists of steels can be created by selecting the appropriate name of the steel standards. Force and load calculations for various deformation processes such as forging, rolling, extrusion and drawing can also be carried out in the relevant modules within the program.

In this study molecular dynamics simulation program in NVT ensemble using Velocity Verlet integration was written in order to investigate the glass forming ability of two metallic systems. The Zn-Mg system, one of the frontiers of simple metal-metal metallic glasses and Fe-B, inquiring attention due to presence of many bulk glass forming alloy systems evolved from this binary with different alloying element additions. In addition to this, atomistic calculations on the basis of ordering were carried out for both Zn-Mg and Fe-B systems. Ordering energy values are calculated using electronic theory of alloys in pseudopotential approximation and elements which increase the ordering energy between atoms were determined. The elements which increase the ordering energy most were selected as candidate elements in order to design bulk amorphous alloy systems. In the experimental branch of the study centrifugal casting experiments were done in order to see the validity of atomistic calculations. Industrial low grade ferroboron was used as the master alloy and pure element additions were performed in order to constitute selected compositions. Fe62B21Mo5W2Zr6 alloy was successfully vitrified in bulk form using nearly conventional centrifugal casting processing. Specimens produced were characterized using SEM, XRD, and DSC in order to detect the amorphous structure and also the crystalline counterpart of the structure when the cooling rate is lower. Sequential peritectic and eutectic reaction pattern was found to be important for metallic glasses which can be vitrified in bulk forms with nearly conventional solidification methods.

The experimental alloy powders of 1% Mg treated Al-8Fe-1.8V-8Si were obtained by air atomization. The screen analysis of powders was made by sieves with meshes ranging from +90&micro / m, +63&micro / m, +53&micro / m, +45&micro / m, +38&micro / m to -38&micro / m. Unreinforced and TiC particulate reinforced specimens were produced by hot dynamic consolidation which is known as hot swaging. Powders were canned into pure aluminium tubes of about 10cm length and 2.2cm diameter. Single action and double action cold pressing were applied to some of the specimens before hot dynamic compaction and some specimens of canned loose powder were also processed. The diameters of the hot compacts were decreased in a two step process by swaging machine (rotary dynamic compaction). During the first step, after canning, compacts had been held at 480&deg / C for 1 hour and swaged, thus the diameter decreased from 2.2 cm to 1.97cm. Secondly, the compacts were reheated to 480&ordm / C and held for 1 hour and further swaged to obtain a diameter decrease from 1.97cm to 1.54cm. Generally, the microstructures of the hot dynamic compacted specimens were homogeneous except the specimens produced by using -63 &micro / m +53 &micro / m powder size fraction. By SEM study, a vanadium free cross like AlFeSi phase was observed near the outer regions of the specimen. No considerable coarsening of the dispersoids was observed after hot dynamic compaction of +63 &micro / m size powder. For -90&micro / m +63&micro / m size powders, maximum flexural strength values obtained by three point bending test increased by addition of 10% TiC to from 152 MPa to 285 MPa at double pressed condition and from 76MPa to 190MPa at loose powder canning condition. By hardness tests, it was observed that hardness values were inversely proportional to powder size and increased from 107 BHN to 147 BHN for corresponding powder size range of +90&micro / m to -38&micro / m. Porosity values obtained by Archimedes principle for single pressing varied between 0.03 % and 1.10% for corresponding size range of +38&micro / m to +90&micro / m. No considerable porosity was detected for double pressing. Porosity values of canned loose powder were between 3% and 10% for the range of +38 &micro / m- +45 &micro / m. By X-Ray analysis, it was revealed that Mg2Si reaction did not form after artificial aging of specimens up to 8 hours at 190&deg / C. Also, x-ray analysis of individual powders and specimens obtained by hot dynamic compaction of the same powder showed that / after hot dynamic compaction, the alloy powders were stable and no new phase formation was detected for +63&micro / m size. DSC examination of the specimens produced from +90&micro / m, +63&micro / m, +53&micro / m, -38&micro / m powder confirmed the microstructure stability up to the melting temperature. Melting temperature was detected to be in the range of 560&deg / C-575&deg / C by DSC.

In this study, the evolution of structure and the relationship between microstructure and corrosion behavior of the Ti-6Al-4V ELI (Extra Low Interstitial) alloy was investigated in Ringer&amp / #8217 / s solution at 37 &plusmn / 0.1 oC. Initially, different heat treatments were performed in order to obtain several microstructures which were / Widmanst&auml / tten &amp / #945 / for furnace cooling (FC), basket-weave &amp / #945 / for air cooling (AC), martensite (&amp / #945 / &#039 / ) for water quenching (WQ) from 1060 oC, and aged martensite for ten hours at 500, 600, 700, 800, 900 oC. The microstructural characterizations were done by using SEM and X-ray Diffraction technique. Finally, the corrosion tests were accomplished in Ringer&amp / #8217 / s solution and NaF added Ringer&amp / #8217 / s solution by using open circuit potential and anodic polarization techniques, respectively. The results showed that vanadium element removal from martensite phase and unit cell volume increase were detected during aging due to the replacement of vanadium with titanium atoms. According to the alloying element distribution throughout the microstructure, the passive film formation due to equilibrium corrosion conditions was better in FC specimen than AC and WQ specimens. But during anodic polarization, the stability of the film in high Cl- ion concentration medium was more resistant to dissolution for WQ and aged specimens. As a result, the alloying element distribution underneath the passive film seemed to have an important role on the film formation and its stability. However, in non-equilibrium conditions, the passive film formation tendency due to the addition of NaF at 0.2M decreased because of the detrimental effects of F- ions.

Pure aluminium and aluminium-5wt % TiO2 aluminium foams were produced by powder metallurgy technique with the use of TiH2 as foaming agent. Two sizes of TiH2 were used: 20&micro / m and 3&micro / m. It has been confirmed that high level of compaction is the primary requirement in foaming. It was shown that hot swaging could be used as a method of compaction for foaming as it leads to values close to full density. Pure aluminium foamed at 675&deg / C and 725&deg / C leads to a volume expansion between 90-180 %. A model was developed for pure aluminium to explain the pore initiation and the resultant pore size. The model predicts a critical particle size for TiH2 below which bubbles could not form. The size appears to be in the neighborhood of 30&micro / m for 675&deg / C and 6&micro / m for 725&deg / C and is temperature dependent. Equilibrium pore size appears to be a function of TiH2 particle size and not affected significantly by the temperature of foaming. It has also been shown that depth effect, i.e. hydrostatic pressure of liquid metal, is unimportant in foaming process and can be neglected. According to the model, to produce pores of fine sizes, two requirements must be met: use of fine foaming agent and the use of high foaming temperature. Al-5 wt % TiO2 was foamed at 750&deg / C and 800&deg / C, i.e. at temperatures that yield viscosities similar to pure aluminium. The structure of foamed metal and level of foaming, 120-160%, was similar to pure aluminium. Unlike pure aluminium, internal reactions are dominant feature of TiO2 stabilized systems. Solid content of the system increases as a result of internal reactions between Al-Ti and Al- TiO2. When this change occurs, however, is not known. It is possible that the viscosity of the system may be four times of its original value.