The master thesis deals with design and manufacturing of rear right formula hub on CNC machining centre by using modern CAD/CAM technologies. The theoretical part is focused on description and characterization of milling technology and machinability of aluminium alloys. The practical part is focused on the designing formula hub in CAD software Pro/Engineer, proposing machining strategies by using CAM software PowerMILL and manufacturing on CNC machine. There is technical economic evaluation of the machined part at the end of the thesis.

This thesis deals with the anodic oxidation of aluminum and its alloys. The work consists of two parts. The first one is focused on more detail description of anodic oxidation process itself and theoretical description of the technological process anodic oxidation. The second part is more practically oriented. It compares two different lines for anodizing, and examines factors that affect the final appearance of the surface layer during anodizing welded joints.

The master's diploma thesis deals with the mechanical and structural characteristics of aluminium-base alloy 2000 series, produced by selective laser melting (SLM). The experimental part of the thesis deal with selection of SLM processing parameters, influence of scanning strategy and evaluation of mechanical and structural characteristics of fabricated materials. Mechanical characteristics were evaluated based on results of tensile tests and microhardness measurement. Structural characteristics of materials produced by SLM were evaluated using metallographic analysis.

Mechanical properties of aluminium alloys highly depend on their phase composition and microstructure. High strength can be achieved among others by introduction of a high volume fraction of fine, homogeneously distributed second phase particles and by a refinement of the grain size. Powder metallurgy allows to prepare fine grained materials with increased solid solubility which are favourable precursors for further precipitation strengthening. Gas atomization was used for the preparation of powders of the commercial Al7075 alloy and its modification containing 1 wt% Zr. A part of gas atomized powders was mechanically milled at different conditions. Mechanical milling reduced the grain size down to the nano-size range and the corresponding microhardness exceeded the value of 300 HV. Powders were consolidated by the spark plasma sintering method to nearly fully dense compacts. Due to a short time and relatively low temperature of sintering the favourable microstructure can be preserved in the bulk material. The grain size of compacts prepared from milled powder was retained in the submicrocrystalline range and the microhardness close to 200 HV exceeded that of the specially heat treated ingot metallurgical counterparts. The prepared compacts retained their fine grained structure and high...

One of the serious problems encountered in the use of various materials in technology is the occurrence of fatigue phenomena as an undesirable material damage under cyclic mechanical load. For aluminium alloys this issue is of extremely high importance in case of their utilisation for aircraft purposes, e.g., where a very wide spectrum of frequencies occur. Moreover, the cyclic loading may be joined by the presence of specific electrolyte media. Therefore, the material candidates must be thoroughly examined in view of their sensitivity to fatigue as well as to corrosion fatigue. Usually, the Cu-containing alloy EN-AW 2024 T3 is applied besides 7075 T6 in Airbus aircrafts, but the weldable alloy 6013 T6 is considered to be a potential alternative. Referring to former investigations on the environmental sensitivity (ES) in the fatigue behaviour /1-6/ this paper brings up experimental findings as well as expanded considerations about damaging mechanisms and modelling. The situation with the alloy 6013 T6 is emphasized. The propagation of cracks under cyclic load in different environments, such as vacuum, air or aqueous media, is described by means of fracture mechanics. This enables discrimination in view of the influence of environmental factors and, hence, the participation of corrosion processes.

Ces travaux de thèse réalisés entre l'IRT Saint Exupéry et le CEMES, Université de Toulouse, CNRS ont pour objet l'étude d’alliages de la série 2000 pour des utilisations à des températures intermédiaires, de l'ordre de 200°C. La possibilité d'utiliser ces matériaux à cette température permettrait aux industriels du secteur aéronautique de réduire les coûts de production d'une part, et de diminuer les coûts d'exploitation des aéronefs ainsi plus légers d'autre part. Afin de répondre à cette problématique industrielle, deux nuances commerciales ont été considérées : le 2219-T851 et le 2050-T84. Ces nuances, déjà utilisées dans l'industrie aéronautique, ont été caractérisées à différentes échelles d'observation tout au long d'un vieillissement isotherme à 200°C allant jusqu’à 10000 h. Des observations effectuées à l'aide de divers microscopes optiques et électroniques et couplées à des essais mécaniques macroscopiques ont permis de déterminer l'évolution de ces nuances vieillies dans de telles conditions. Les résultats de cette étude montrent une importante stabilité thermodynamique des précipités nanométriques θ'-Al2Cu. Ces précipités constituent la microstructure fine de la nuance 2219-T851 à réception et apparaissent au cours du vieillissement au sein de la nuance 2050-T84 au détriment des précipités T1-Al2CuLi pourtant à l'origine des meilleures performances mécaniques avant vieillissement. Les évolutions microstructurales sont mises en lien avec les propriétés mécaniques en traction. Ces résultats montrent un intérêt industriel pour la nuance 2219-T851 dont la stabilité des propriétés a été montrée dès 1000h de vieillissement. / The main objective of this work which has been conducted between the IRT Saint Exupéry and the CEMES, Université de Toulouse, CNRS laboratory is to reduce production and exploitation costs of aircraft primary structures by evaluating the potential increase of operating temperatures of aluminum alloys. To do so, two already fit-to-fly Al-Cu alloys have been selected and studied: the 2219-T851 and the 2050-T84. These alloys have been characterized throughout ageing treatments up to 10,000h at 200°C with electronic and optical microscopies in order to evaluate the microstructural changes. Standardized mechanical tests have also been conducted to follow the effects of such ageing on the alloys’ properties. The results have shown the stability of the mechanical properties and the microstructure of the 2219-T851 from 1,000h to 10,000h of ageing. This is attributed to the nano-precipitation of θ'-Al2 Cu, stable during the ageing treatment. Moreover, those precipitates tend to form during the ageing of the 2050-T84 by replacing the well known T1-Al2CuLi phase, unstable during medium range temperature ageing. During this thesis, special attention has been paid on the link between the mechanical properties and the fine scale microstructures of both alloys.

Aluminium alloys have the possibility to be infinitely recycled. By only generating 5% of the emissions compared to primary aluminium, great CO2 savings can be made. One of the issues in manufacturing components entirely from post-consumer scrap is the presence of trace elements and impurities. Such elements can be Fe, Cu, Cr, P and Pb. In sheet metal manufacturing, these elements can also react with process agents such as Ti, B, Na and Sr and affect the recrystallization behavior and in turn mechanical properties.In this work, a derivative of the 3003 alloy made entirely from post-consumer scrap has been analysed. The alloy achieved insufficient formability due to lack of recrystallization and grain growth. With the use of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) together with focused ion beam (FIB) lamella preparation, the microstructure was characterized.The characterization shows both larger particles of α-Al15Si2M4 (M=Mn,Fe,Cr) from solidification and dispersoids from heat treatment, pinning the grain boundary movement together with Q-AlCuMgSi. With the use of high throughput computational thermodynamics, Thermo-Calc was used to effectively screen compositions lowering the amount of α-Al15Si2M4 and removing the Q-AlCuMgSi phase. The new alloy was cast using directional solidification at different cooling rates to study the particle morphology, which in turn plays a role in the particle break up and distribution during cold working as the interparticle spacing affects the grain growth.Varying cooling rates was seen to affect morphology and distribution. Hot compression was utilized to examine the particle redistribution before cold work. It was however shown that hot compression was not sufficient in redistributing the particles as would be the case in rolling.

[pt] O método EN baseia-se na quantificação do dano causado pela deformação decorrente do histórico de carregamento. O objetivo desse modelo consiste em estimar o número de ciclos para iniciar uma trinca por fadiga. Diferente do método SN o número de variáveis envolvidas nesse modelo é menor. Entretanto, requer um número maior de constantes, que nem sempre podem ser obtidas experimentalmente. Esse fato levou a formulação de diversos modelos que se propõem a estimar as constantes de Coffin-Manson, que na maioria dos casos levam a previsões de vida não conservativas, como visto em outros trabalhos. Contudo a maioria dos casos existentes na literatura não abordam o efeito de regiões de concentração de tensão e a influência de carregamentos com amplitudes variáveis. A metodologia usada nessas pesquisas consiste em avaliar a influência desses aspectos através da comparação entre a vida em fadiga experimental e a estimada segundo as constantes de Coffin-Manson medidas e estimadas segundo diferentes modelos. Esse estudo avalia o dano à fadiga segundo 2 tipos de concentradores de tensão e quatro históricos de carregamentos de amplitude variável. Considerando os modelos de Manson, Muralindhran-Manson, Bäumel-Seeger and Meggiolaro-Castro os resultados mostram que a vida em fadiga prevista usando os parâmetros de Coffin Manson obtidos segundo o método de Meggiolado-Castro e por Baumel-Segger são os que mais se aproximam das vidas estimadas baseada nas constantes experimentais. Nos demais casos nota-se que a regra de concentração de tensão exerce uma maior influência no resultado e levam a vidas à fadiga não conservativas. / [en] The strain-life designed is based on the damaged caused by the strain as a result of a loading history. The purpose of this approach is estimating the number of cycles to initiate a fatigue crack. Compared with the stress life method the EN needs a lower number of variables. However, it needs a large number of parameters that are not directly measurable properties of a material and conduct the necessary number of tests to obtain them is not always an option. This fact leads to the formulation of different models to estimate Coffin- Manson s constants, which in most of the cases can result in a non-conservative fatigue life prediction, as seen in several papers. However, in these studies, it is not considered a specimen with a stress concentration factor neither under a variable amplitude loading history. The methodology used in this research is evaluating the influence of these aspects by comparing the fatigue life experimental with the estimated by using the Coffin Manson s experimental constants and the fatigue life calculated with different models to estimate the Coffin-Manson s parameters. This study evaluated the fatigue damage based on four load histories and two types of samples with different stress risers. Considering the models of Manson, Muralidharan-Manson, Bäumel-Seeger, and Meggiolaro-Castro the results indicated that the fatigue life predicted using the Coffin Manson s parameter obtained by Meggiolaro-Castro and Baumel-Segger s model are more similar to the life calculated with the experimental constants. The other models are more influenced by the stress concentration s rule and can lead to not conservative fatigue life.

Commercial alloys are continuously developed to improve their performance. Therefore it is important to develop new optimisation software, which could be used in development of new materials or in materials selection. In this study the mechanical properties which are important in materials selection in mechanical design are investigated. Two types of materials are analysed, aluminium alloys and stainless steels but focus will be on the aluminium alloys. Thermodynamic analysis has been used to evaluate the effect of the microstructure. Solid solution hardening has been successfully modelled for both aluminium alloys and stainless steels and follows the theories by Labusch and Nabarro. The precipitation hardening is most dominant for the hardenable aluminium alloys, but the non-hardenable alloys also increase their strength from precipitation hardening. The non-hardenable alloys are divided into tempers, which differ in the amount of strain hardening. This has also been modelled successfully. Combining these fundamental results with multiple regression, models for mechanical properties have been created. Separate models are developed for wrought aluminium alloys and stainless steels. For the aluminium alloys this includes the solid solution hardening and the precipitation hardening. For the stainless steels the thickness, nitrogen content and ferrite content are included together with the solid solution hardening. / QC 20101122

The glass-forming composition ranges in Al-La-Ni and Mg-TM (Cu, Zn)-Y alloys were predicted using Miedema’s model. Glass-forming abilities of Al-La-Ni alloys and Mg-Cu-RE alloys were studied in terms of reduced glass transition temperature (Trg), supercooled liquid region (∆Tx) and γ parameters. The glass-forming ability parameters of Mg-Cu-RE (RE: rare-earth) alloys were correlated with Mendeleev number. The Miedema model has been used to determine glass-forming composition range in binary Al-La, Al-Ni and La-Ni alloy systems and the ternary Al-La-Ni system by neglecting the ternary interactions. The glass-forming composition range for Al-La, Al-Ni and La-Ni alloy systems extends from 5 to 90 at% La, 30 to 80 at% Ni and 5 to 95 at% Ni, respectively. In these systems the predicted glass-forming composition range is wider than the experimentally observed range. Miedema model, restricting the difference of enthalpy of formation between the amorphous and solid solution phases to within –10000 J/mole to –55000 J/mole gives rise to better prediction of glass-forming composition range compared to the original models. The concept of mixing enthalpy and mismatch entropy has been used in order to quantify Inoue’s criteria of glass formation. The mixing enthalpy and normalised mismatch entropy of the ternary Al-La-Ni alloys, calculated by the extended regular solution model, vary between –12 to –40 kJ/mol and 0.16 to 0.65, respectively. The enthalpy contour plot has been constructed to distinguish the glass-forming compositions on the basis of the increasing negative enthalpy of the composition. Six Al rich Al-La-Ni alloys with nominal compositions Al89La6Ni5, Al85La10Ni5, Al85La5Ni10, Al82La8Ni10, Al80La10Ni10 and Al60La20Ni20 three La rich Al-La-Ni alloys with nominal compositions Al34La33Ni33, Al40La40Ni20 and Al25La50Ni25 have been chosen from the Al-La-Ni ternary phase diagram, to study the glass-forming ability of Al-La-Ni ternary alloy system and the correlation between La-based and Al-based glasses. All the alloys have been prepared using arc melting unit. All the alloy ribbons have been prepared using single-wheel vacuum melt-spinning unit. Two different wheel speeds of 20 m/s and 40 m/s were used for preparing ribbons of all the nine alloys. All the Al-La-Ni compositions, excluding equi-atomic composition (Al34La33Ni33) and Al60La20Ni20, give rise to amorphous phases. The supercooled liquid region and reduced glass transition temperature of this system increases with a decrease in Al content and an increase in La content. The glass-forming ability of the Al rich Al-La-Ni alloys is lower than that of the La-rich Al-La-Ni alloys. The glass-forming ability has been explained by taking into account the binary heat of mixing and the atomic radius mismatch of the constituent elements. Preferential crystallisation takes place during the heat treatment of glassy ribbons. The crystalline products are partially influenced by composition and binary heat of mixing between elements. Mg65Cu25Y10 alloy is a classical glass former of a family of Mg-based alloys. The partial or complete substitution of Y with other rare earth elements has been introduced to correlate the Mendeleev Number with the glass-forming ability parameters: reduced glass transition temperatures (Trg = Tg/Tl), supercooled liquid regions (∆Tx = Tx – Tg) and γ-criterion (TX/(Tg + Tm)). Mg-Cu-RE alloys with nominal compositions Mg65Cu25Y10, Mg65Cu25Y5Gd5, Mg65Cu25Y5Nd5, Mg65Cu25Gd10 and Mg65Cu25Nd10 were chosen for this work. The high reduced glass transition temperature, wider supercooled liquid region and higher γ value of Mg-Cu-Gd-Y amorphous alloy compared to Mg-Cu-Y and Mg-Cu-Nd-Y systems indicates that Mg-Cu-Gd-Y alloys possess higher glass-forming ability. The devitrification of all Mg-Cu-RE glassy alloys used for this work give rise to Mg2Cu (oF48) phase, which is known as anti-Laves phase. The glass-forming composition range for binary and ternary Mg-Cu-Y systems was calculated using Miedema’s model. The development of accurate methods of prediction of glass-forming ability in metallic systems is an important challenge. Pettifor has pioneered the Structure Mapping approach to binary intermetallics. The Pettifor approach can be adapted to the designing of bulk metallic glasses (BMGs). This method has been used to design Al-based and Mg-based BMG’s. Pettifor introduced an integer parameter to characterize the elements, which he called the Mendeleev Number. Essentially, Pettifor’s scheme orders the elements in a sequence of increasing electronegativity. With respect to Mendeleev Number, the Mg-Cu-RE system can be regarded as a binary system, because of the closeness of Mg and Cu (Mg:73, Cu:72, Y:25, Gd:27 and Nd:30). For this system, Mendeleev Number is a more effective parameter than atomic size (Mg: 1.60 Å, Cu: 1.27 Å), as a predictor of glass-forming ability. The effect of Y and rare earth elements on glass forming ability is similar. The atomic number of Y (39) is away from that of the rare earth elements and the Mendeleev Number of Y (25) comes in between those of the rare earth elements. Mg-Zn-Y system is an interesting system for researchers because of higher strength of these alloys. This system draws the crystallographers’ attention due to its composition-dependent structure variations. The Mg-rich RS/PM Mg-Zn-Y alloys yield superior mechanical properties. Therefore, the Mg-rich Mg-Zn-Y system has been chosen to study the microstructural evolution, even though the theoretical calculations for the glass-forming composition range for the Mg-Zn-Y system shows that this system is not a good glass former. Mg-Zn-Y system with nominal compositions Mg97Zn1Y2, Mg97Zn2Y1, Mg97−xZn1Y2Zrx and Mg92Zn6.5Y1.5 were chosen to study the microstructural evolution of these alloys. A small increase in Zn amount (above 2 at.%) in Mg-rich Mg-Y system results in quasicrystalline particles embedded in the matrix, whereas the addition of Zn up to 2 at.% leads to microstructural changes in the α-Mg solid solution.