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Abstract 
Titanium is the fourth most abundant structural metal in the world. It is known to have a high strength, light weight, good formability and high corrosion resistance. Due to these properties, Titanium and its alloys are used in many industries, such as aerospace and automobile. Note that due to its high price, one can find Ti6Al4V in demanding applications. 
This master thesis defines quantitatively predicting of the microstructure of a titanium alloy, Ti6Al4V, worked with laser cladding process. The main goal is to define the proper phase transformation conditions that lead to reliable phase predictions. 
Outcomes are checked from the results obtained by two experimental observations in laser cladding process for the Ti6Al4V. Both studies obtained qualitative results according to the phases that formed the microstructure of the alloy and the hardness value of three different points located in the deposits. As a first reference, H.S. Tran used Constant Track Length building strategy. The second study has been made by MMS team at University of Liège, but it has not been published yet. They used a Decrease Track Length building strategy. The initial experimental work was done by H.Paydas .
This master thesis is based on the implementation of a Fortran code that defines the phase transformations of Ti6Al4V. Inside the code, the thermal conditions and the equations with their parameters are defined. The project was based on Crespo’s model that calculates the phase transformation kinetics of this titanium alloy. After applying the same model, some differences have been made in order to achieve the desired results according to the improvement works done by H.S Tran and MMS team. 
This document presents a flow work starting with the basic theoretical background about Additive Manufacturing, Titanium and its alloys. After, Ti6Al4V is presented: its chemical composition, the different phases that can describe its microstructure and the equations that define the transformations from one phase to the other. The parameters and conditions defining those equations are determined and compared with previous literature, concretely with Crespo. Finally the results and conclusions are presented. 
Keywords: Laser Cladding (LC), Ti6Al4V, microstructure, thermal history, Fortran.

Laser Cladding (LC), Ti6Al4V, microstructure, thermal history, Fortran. --- Ingénierie, informatique & technologie > Science des matériaux & ingénierie

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Ce travail de fin d'études a pour but d'entamer le développement de matériaux à gradients de composition et de bi-matériaux entre le cuivre et l'inox par la technique de laser cladding.

Pour se faire, l'influence de paramètres tels que la vitesse, la puissance du laser ou même le flux de poudre va être testée. Cette étude des paramètres aura d'abord lieu dans le cas de simples cordons de soudures pour ensuite s'étendre à la construction de couches puis de murs en cuivre et en inox. La validation des différents paramètres se fera au microscope optique par l'observation de caractéristiques spécifiques aux cordons, couches ou murs. Une analyse de la diffusion des différents éléments et de la microstructure sera réalisée par SEM couplé à l'EDS dans le cas des cordons.

Grâce à cette recherche de paramètres, une corrélation a été proposée dans le but de former des murs avec différentes proportions en cuivre et en inox. Ces essais avec différentes compositions par la technique de laser cladding sont assez novateurs. Ces premiers essais ont montré une bonne justesse de la corrélation ainsi que plusieurs phénomènes inattendus. Ces murs ont également été analysés par DRX.
Les propriétés mécaniques des différents murs purs et avec différentes compositions seront analysées par nanoindentation.

L'étude des différents paramètres dans ce travail a permis la construction de murs solides en cuivre, en inox ou avec différentes proportions. Ce travail a permis également d'obtenir une première vue des murs avec différentes compositions. La dureté et le module de Young sont renforcés avec l'augmentation de la proportion en inox et ils sont affaiblis avec l'augmentation de la proportion en cuivre. The aim of this work is to begin the development of materials with compositional gradients and bi-materials between copper and stainless steel using the laser cladding technique.

For this purpose, the influence of parameters such as speed, laser power or even powder flow will be tested. This study of parameters will first take place in the case of simple weld beads and will then be extended to the construction of layers and then walls in copper and stainless steel. Validation of the different parameters will be done under an optical microscope by observing specific characteristics of the weld beads, layers or walls. An analysis of the diffusion of the different elements and of the microstructure will be carried out by SEM coupled with EDS in the case of the weld beads.

Thanks to this research of parameters, a correlation was proposed in order to form walls with different proportions of copper and stainless steel. These tests with different compositions using the cladding laser technique are quite innovative. These first tests showed a good accuracy of the correlation as well as several unexpected phenomena. These walls were also analyzed by DRX.
The mechanical properties of the different pure walls with different compositions will be analysed by nanoindentation.

The study of the different parameters in this work allowed the construction of solid walls in copper, stainless steel or with different proportions. This work has also made possible to obtain a first view of the walls with different compositions. The hardness and Young's modulus are reinforced with the increase of the stainless steel proportion and they are weakened with the increase of the copper proportion.

Laser cladding --- Inox --- Cuivre --- Paramètres --- Gradients --- Microdureté --- Ingénierie, informatique & technologie > Ingénierie chimique

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In this work the SS316L + SiC Metal Matrix Composites (MMCs) was characterized. Different amount of Silicon Carbide (SiC) was added as reinforcements in a matrix of 316L Stainless Steel (SS316L): 10% in volume and 20% in volume. The composites were produced by Laser Cladding (LC). 
An evolution of the characteristics of the cladded deposit was observed with the change of LC process parameters, such as power, scanning speed and powders utilized. For the production of SS316L + 20% SiC deposit the powders were used in original (as-produced) and milled conditions. While for the SS316L + 10% deposit only original powders were utilized. 
The deposits with 10% in volume of original SiC powders and with 20% in volume of milled SiC powders exhibit a compact structure with absence of porosity and/or cracks, and good interaction with the substrate.
The characterization was made by means of Optical Microscope (OM), Scanning Electron Microscope (SEM), Differential Thermal Analysis (DTA), Thermo Gravimetry Analysis (TGA), Macro-hardness tests and chemical analysis. 
The powders of the two different compositions and after the milling process were characterized, especially by different thermal analysis and microscope observations. Considering their characteristic, the best condition for the Additive Manufacturing (AM) process was chosen and the samples were fabricated by LC. The microstructural characterization on the deposits revealed the formation of carbides that reinforce the matrix. The morphology and the composition of phases of the different deposits were compared by using microscope observations and thermal analyses.

Additive Manufacturing (AM), Laser Cladding (LC), Metal Matrix Compoites (MMCs), 316L Stainless Steel, 316L Stainless Steel + SiC --- Ingénierie, informatique & technologie > Science des matériaux & ingénierie

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The book “Surface Treatment by Laser-Assisted Techniques” presents state-of-the-art research applications of lasers for surface modification. Applications in a broad spectrum of fields are presented: the aircraft and automotive sector, the manufacturing industry, sensor development, electronics, biomedical engineering, or the energy sector. Several radiation sources are included, from pulsed lasers in the visible and near-infrared regions to continuous-wave mid-infrared laser sources. The different chapters of the book “Surface Treatment by Laser-Assisted Techniques” cover laser texturing at nanoscale and microscale for modification of hydrophobicity, hydrophilicity, and ice nucleation; the production of palladium, platinum and silver nanoparticles for sensor applications; the texturization of composite bioceramics for improved fixation in bone prosthesis; the surface texturization of natural ceramic materials by scanned laser radiation; the laser ablation of interfaces to enhance adhesion in dissimilar joints; the analysis of material thermoelastic response; and the production of highly polished topographies in pulsed laser surface modification. Moreover, the production of high-entropy alloy/diamond composite coatings, the modellization of the gas-powder injection, and the generation of thermal barrier coatings by laser cladding are reported in the last chapters of this book.

Engineering --- Technology --- Pd --- Pt --- FTO --- laser irradiations --- dewetting --- nanoparticles --- surface treatment --- CO2 laser --- scanning system --- granite stone --- dual-beam --- beam shaper --- MPFV method --- laser polishing --- zigzag-square wave --- bioceramics --- laser ablation --- roughness --- composites --- hip joint prosthesis --- cementless cup --- bone --- silver nanoparticles --- electrophoretic deposition --- pulsed laser ablation in liquid --- laser welding --- metal-polymer --- thermal contact resistance --- generalized thermoelasticity --- laser radiation --- volumetric absorption --- thermal stresses --- cooling effect --- laser cladding --- diamond composite coating --- high entropy alloy --- high scanning speed --- wear resistance --- laser-cladding --- La2Zr2O7 thermal barrier coating --- Ni-based superalloy --- high temperature oxidation --- thermal shock --- extreme high-speed laser material deposition (EHLA) --- laser material deposition (LMD) --- coaxial powder nozzle --- coating --- additive manufacturing --- numerical simulation --- hydrothermal treatment --- micro/nano-hierarchical structures --- wetting model --- anti-icing --- History. --- History. --- Pd --- Pt --- FTO --- laser irradiations --- dewetting --- nanoparticles --- surface treatment --- CO2 laser --- scanning system --- granite stone --- dual-beam --- beam shaper --- MPFV method --- laser polishing --- zigzag-square wave --- bioceramics --- laser ablation --- roughness --- composites --- hip joint prosthesis --- cementless cup --- bone --- silver nanoparticles --- electrophoretic deposition --- pulsed laser ablation in liquid --- laser welding --- metal-polymer --- thermal contact resistance --- generalized thermoelasticity --- laser radiation --- volumetric absorption --- thermal stresses --- cooling effect --- laser cladding --- diamond composite coating --- high entropy alloy --- high scanning speed --- wear resistance --- laser-cladding --- La2Zr2O7 thermal barrier coating --- Ni-based superalloy --- high temperature oxidation --- thermal shock --- extreme high-speed laser material deposition (EHLA) --- laser material deposition (LMD) --- coaxial powder nozzle --- coating --- additive manufacturing --- numerical simulation --- hydrothermal treatment --- micro/nano-hierarchical structures --- wetting model --- anti-icing

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The book “Surface Treatment by Laser-Assisted Techniques” presents state-of-the-art research applications of lasers for surface modification. Applications in a broad spectrum of fields are presented: the aircraft and automotive sector, the manufacturing industry, sensor development, electronics, biomedical engineering, or the energy sector. Several radiation sources are included, from pulsed lasers in the visible and near-infrared regions to continuous-wave mid-infrared laser sources. The different chapters of the book “Surface Treatment by Laser-Assisted Techniques” cover laser texturing at nanoscale and microscale for modification of hydrophobicity, hydrophilicity, and ice nucleation; the production of palladium, platinum and silver nanoparticles for sensor applications; the texturization of composite bioceramics for improved fixation in bone prosthesis; the surface texturization of natural ceramic materials by scanned laser radiation; the laser ablation of interfaces to enhance adhesion in dissimilar joints; the analysis of material thermoelastic response; and the production of highly polished topographies in pulsed laser surface modification. Moreover, the production of high-entropy alloy/diamond composite coatings, the modellization of the gas-powder injection, and the generation of thermal barrier coatings by laser cladding are reported in the last chapters of this book.

Pd --- Pt --- FTO --- laser irradiations --- dewetting --- nanoparticles --- surface treatment --- CO2 laser --- scanning system --- granite stone --- dual-beam --- beam shaper --- MPFV method --- laser polishing --- zigzag-square wave --- bioceramics --- laser ablation --- roughness --- composites --- hip joint prosthesis --- cementless cup --- bone --- silver nanoparticles --- electrophoretic deposition --- pulsed laser ablation in liquid --- laser welding --- metal–polymer --- thermal contact resistance --- generalized thermoelasticity --- laser radiation --- volumetric absorption --- thermal stresses --- cooling effect --- laser cladding --- diamond composite coating --- high entropy alloy --- high scanning speed --- wear resistance --- laser-cladding --- La2Zr2O7 thermal barrier coating --- Ni-based superalloy --- high temperature oxidation --- thermal shock --- extreme high-speed laser material deposition (EHLA) --- laser material deposition (LMD) --- coaxial powder nozzle --- coating --- additive manufacturing --- numerical simulation --- hydrothermal treatment --- micro/nano-hierarchical structures --- wetting model --- anti-icing --- n/a --- metal-polymer --- Engineering --- Technology --- History.