Obróbka elektroerozyjna spieków na osnowie fazy międzymetalicznej feal bez i z dodatkiem nanoceramiki Al2O3

The influence of the parameters of wire electrical discharge machining (WEDM) on the surface layer of FeAl based sinters with and without Al2O3 nanoceramic addition has been studied in this paper. The properties of the sinters surface layer were controlled by WEDM parameters, including time of interval (tp) and amplitude of current (IA). The WEDM roughing and finishing treatments were carried out for selected technological parameters of process. The surface texture (ST) of the sinters after WEDM was analyzed by profilometer method. Theoretical parameters describing abrasive wear resistance of investigated sinters were estimated on the basis on the load capacity curve. On the basis on obtained results it can be stated that there is possibility of shaping geometry of nano- Al2O3 doped and undoped FeAl sinters by WEDM. Reduction of the time of interval (t p) and increase of current amplitude (IA) during WEDM deteriorate surface properties. Addition of nano- Al2O3 improve the quality of the obtained surface. Applied parameters of WEDM improve theoretical abrasive wear resistance and lubricant maintenance of the nanoceramic doped material in comparison with undoped sinter.W niniejszej pracy analizowano wpływ parametrów cięcia elektrozyjnego (ang. WEDM – wire electrical discharge machining) na warstwę wierzchnią spieków na osnowie fazy międzymetalicznej FeAl bez i z dodatkiem nanoceremiki Al2O3. Poprzez zmianę parametrów obróbki elektroerozyjnej, tj. czas przerwy (tp) i natężenie prądu (IA), sterowano właściwościami warstwy wierzchniej obrabianych spieków. Dla wybranych parametrów technologicznych procesu przeprowadzono obróbkę zgrubną i wykańczającą. Strukturę geometryczną powierzchni (SGP) spieków po obróbce elektroerozyjnej analizowano za pomocą metody profilometrycznej. Parametry charakteryzujące teoretyczną odporność na zużycie ścierne zostały oszacowane na podstawie krzywych nośności Abbotta-Firestone’a. Na podstawie uzyskanych wyników stwierdzono, że istnieje możliwość kształtowania geometrii spieków FeAl bez i z dodatkiem nanoceramiki Al2O3 za pomocą obróbki elektroerozyjnej WEDM. Wraz ze skróceniem czasu przerwy i wzrostem natężenia prądu podczas obróbki wzrasta chropowatość obrabianych powierzchni, natomiast dodatek nanoceramiki poprawia jakość otrzymanych powierzchni. Zastosowane parametry obróbki WEDM poprawiły teoretyczną odporność na zużycie ścierne i zdolność do przechowywania środka smarnego powierzchni spieków domieszkowanych nanoceramiką, w porównaniu do materiału niedomieszkowanego

The Effect of Nanometric α-Al2O3 Addition on Structure and Mechanical Properties of Feal Alloys Fabricated by Lens Technique

Results of the first principle study on a fabrication of FeAl intermetallic based alloy with an addition of nanometric αAl2O3 (n-Al2O3) particles by the LENS method and a subsequent characterization of the as received materials’ structure and properties, are shown in the present work. A series of samples were manufactured using LENS technique while a control of temperature and the size of melted metal pool. The presence of ceramics nanoparticles was not directly confirmed by microscopy observations. Neither aluminum nor oxygen content was not elevated in the material with n-Al2O3 content. Although, indirect methods revealed influence of n-Al2O3 addition on the manufactured elements structure. Analyses of porosity has shown that addition of 2% vol. n-Al2O3 significantly decreases this feature (~1%), as compared to the reference material made of pure FeAl intermetallic alloy (~5%). The addition of n-Al2O3 causes an increase of grain size in Fe40Al intermetallic alloy. An oxidation resistance has been also improved what was associated to the n-Al2O3 addition. Four times lower increase of samples mass was noticed for sample with the n-Al2O3 addition as compared to the pure Fe40Al intermetallic alloy

The Effect of Nanometric α-Al2O3 Addition on Structure and Mechanical Properties of Feal Alloys Fabricated by LENS Technique

Results of the first principle study on a fabrication of FeAl intermetallic based alloy with an addition of nanometric αAl2O3 (n-Al2O3) particles by the LENS method and a subsequent characterization of the as received materials’ structure and properties, are shown in the present work. A series of samples were manufactured using LENS technique while a control of temperature and the size of melted metal pool. The presence of ceramics nanoparticles was not directly confirmed by microscopy observations. Neither aluminum nor oxygen content was not elevated in the material with n-Al2O3 content. Although, indirect methods revealed influence of n-Al2O3 addition on the manufactured elements structure. Analyses of porosity has shown that addition of 2% vol. n-Al2O3 significantly decreases this feature (~1%), as compared to the reference material made of pure FeAl intermetallic alloy (~5%). The addition of n-Al2O3 causes an increase of grain size in Fe40Al intermetallic alloy. An oxidation resistance has been also improved what was associated to the n-Al2O3 addition. Four times lower increase of samples mass was noticed for sample with the n-Al2O3 addition as compared to the pure Fe40Al intermetallic alloy

Self-Organized Anodic Oxides on Titanium Alloys Prepared from Glycol- and Glycerol-Based Electrolytes

The anodization of commercially pure Ti alloy (99.5 wt %) and two biomedical titanium alloys, Ti6Al7Nb and Ti6Al4V, was performed, and the resulting anodic oxides were studied. The biomedical alloys were made by Laser Engineered Net Shaping. The glycol-based and glycerol-based electrolytes with 0.3 M ammonium fluoride and 2 wt % of deionized water content were tested. It was found that electrolyte type as well as the chemical composition of the base substrate affected the final morphology and chemical composition of the anodic oxide formed. A higher current density, ionic mobility, and oxide growth rate were obtained in glycol-based electrolyte as compared to those obtained in glycerol-based electrolyte for all tested alloys. A self-organized nanotubular and nanoporous morphology of the anodic oxide in both types of electrolyte was obtained. In each electrolyte, the alloy susceptibility to oxidation increased in the following order: Ti6Al4V < Ti 99.5% < Ti6Al7Nb, which can be correlated to the oxidation susceptibility of the base titanium alloy. It was observed that the more impurities/alloying elements in the substrate, the lower the pore diameters of anodic oxide. There was a higher observed incorporation of electrolyte species into the anodic oxide matrix in the glycerol-based electrolyte compared with that in glycol-based electrolyte

Boron Enhanced Complex Concentrated Silicides – A bridge between lightweight, oxidation-resistant Refractory Metal Silicides and Refractory Complex Concentrated Alloys

This study presents the Boron Enhanced Complex Concentrated Silicides (BECCSs) as a novel category of high-temperature materials derived from the high entropy concept. Using a quaternary MoNbTaW equiatomic alloy as a starting point, four new alloy compositions were designed in a multi-step process oriented towards reducing the density of the material. By incorporating different combinations of Ti, Si, and B, the phase composition of the materials was altered from a BCC solid solution to a multi-phase structure consisting of BCC solid solution and various intermetallics (silicides, borides, and borosilicides). The suggested modification of the alloy composition led to a significant decrease in density, reaching down to 6.87 g/cm3. All four alloys were fabricated by the arc melting technique, while their microstructure and room temperature mechanical properties were evaluated by SEM/EDS/EBSD and micro-indentation methods. The results of structural characterization enabled the identification of specific phase constituents. Consequently, it was established that the transition from BCC solid solutions to silicides/borides based alloys results in a significant increase in hardness, achieving up to 1200 HV (13 GPa)

Boron Enhanced Complex Concentrated Silicides – New pathway for designing and optimizing ultra-high temperature intermetallic composite materials

Refractory Metal Intermetallic Composites and Refractory Complex Concentrated Alloys have been identified as promising candidates for ultra-high-temperature applications that exceed the limits of superalloys. However, designing and developing new materials with the proper density for aerospace applications is a significant challenge. For this reason, new refractory metal-based materials are in continuous development. This study introduces a new class of materials known as Boron-Enhanced Complex Concentrated Silicides (BECCSs). By providing a balance between density and high-temperature performance, these materials with their density-optimized refractory metal silicide-borides have the potential to revolutionize high-temperature applications. Utilizing a quaternary MoNbTaW equiatomic alloy (ρ = 13.73 gcm−3) as a starting point and a computer-aided alloy modeling tool, seven alloy compositions were designed in a multi-step process aimed at lowering the material density. Through the introduction of Ti, Si, and/or B, the microstructure was transformed from a BCC solid solution to a multiphase structure comprised of silicides and borides. The proposed redesign of the alloy led to a significant reduction in density, even to 5.44 gcm−3. All seven alloys were produced by using a laboratory arc melter, and their microstructure and room-temperature mechanical properties were analyzed using SEM, EDS, EBSD, and micro-indentation. The results of structural characterization allowed us to identify specific phase constituents, and it was established that a transition from BCC solid solutions to silicides/borides-based alloys results in a substantial increase in hardness, even above 1600 H V (17 GPa)