This study investigated the control of porosity during gas metal arc welding with pulsed arc (GMAW-P) of complex-phase 780 (CP780) galvanized steel. Due to the Zn coating on this type of steel, porosity forms during welding as a result of Zn vaporization. The objective was to optimize the welding parameters to minimize porosity with a design of experiments using an L9 orthogonal array to analyze the effects of peak current (I_p), pulse time (t_p), and pulse frequency (f) in high-speed welding conditions. The results showed that porosity was significantly reduced with a peak current of 313 A, a frequency of 10 Hz, and a pulse time of 10 ms, achieving ~0% porosity in the validation welding trials. A microstructural analysis identified allotriomorphic ferrite, Widmanstätten ferrite, acicular ferrite, bainite, and martensite in the heat-affected zone (HAZ). A predictive model to anticipate the percentage of porosity with an R² of 99.97% was developed, and an ANOVA determined the peak current as the most critical factor in porosity formation.

To purpose of this work is to determine the biocompatibility of the Zr₅₈Co₂₁Al₉Ag₁₂ alloy; vitreous ribbons of the Zr₅₈Co₂₁Al₉Ag₁₂ alloy were obtained by a chill block melt spinner. They were characterized by X-ray diffraction and transmission electron microscopy. Chemical homogeneity was examined by scanning electron microscopy. Similarly, thermal analysis was performed using differential scanning calorimetry. The nanoindentation test was performed with a Berkovich nanoindenter. Subsequently, the bioactivity was evaluated by chemical immersion in simulated body fluid. After immersion, it was characterized by XRD. A cell adhesion test was performed using mesenchymal stem cells from human dental pulp. Cell viability and proliferation were evaluated with a CCK-8 assay using human lymphocytes. The ribbons have crystalline phases close to 20%. The thermal parameters, Young’s modulus, and hardness were obtained. After the immersion test, Ca and P were identified. Ion release does not exceed critical levels for human cells. The alloy has a higher concentration of adhered cells compared to Ti₆Al₄V. The alloy remains bio-inert with respect to apatite formation; however, it exhibits excellent cell viability, proliferation, and adhesion behavior.

The effect of the partial substitution of Al for Ag in the glass forming ability (GFA) of the Zr_57.52Co_21.24Al_21.24-xAg_x (x = 8, 10, 12, and 14 at. %) family alloy are reported and discussed. Cylindrical and conical ingots were obtained using the suction casting technique. It was found that the Zr_57.52Co_21.24Al_9.24Ag₁₂ alloy showed a glassy structure, with a critical glassy diameter, D_c, of 2 mm and ∆T_x = 41 K. The bulk metallic glass Zr_57.52Co_21.24Al_9.24Ag₁₂ alloy was examined using scanning electron microscopy, differential thermal analysis and mechanical compression test. This alloy showed a Young´s modulus (E) of 76.4 GPa and yield strength (σ_y) of 1.58 GPa. The Glass Forming Ability of the Zr_57.52Co_21.24Al_9.24Ag₁₂ was explained in terms of the topological model of dense packed clusters and kinetic fragility index of the alloy.

In this work, the Zn22Al4Ag alloy was synthesized by melting in a muffle furnace.The alloy obtained was characterized by Scanning Electron Microscopy Energy Dispersive Spectroscopy and was analyzed by the X-Ray Diffraction technique, where the crystallinity of the material was verified before and after being processed. Likewise, the Differential Scanning Calorimetry technique was used to obtain the temperatures where phase transformations occurin the alloy. These results were fed to the Termocalc®, software to numerically obtain the phase diagram of the alloy. Subsequently, a section of the ingot was taken to the rapid solidification process by rotating drum. The process variables were manipulated: jet stability, nozzle diameter, distance from the nozzle surface to the cooling medium, the delay time of the molten material in the crucible, speed of the rotating drum and jet angle, until obtaining a microwire with a diameter of ~ 160µm. Finally, it was determined that inadequate control of these parameters can result in powders, flakes or blockage of the crucible outlet. Potentially uses within the micro and nanoworld as an analogy to structural elements and electrical conductors, in addition to its current use as a coating anti-corrosive. Key Words: ZnAlAg alloy, Melt spinning process, Microwire, DSC analysis, Thermodynamic simulation En este trabajo se sintetizó la aleación Zn22Al4Ag mediante fusión en horno de mufla. La aleación obtenida se caracterizó mediante Espectroscopia de Dispersión de Energía por Microscopía Electrónica de Barrido y se analizó mediante la técnica de Difracción de Rayos-X, donde se verificó la cristalinidad del material antes y después de ser procesado. Asimismo, se utilizó la técnica de Calorimetría Diferencial de Barrido para obtener las temperaturas donde se producen las transformaciones de fase en la aleación. Estos resultados se introdujeron en el software Termocalc®, para obtener numéricamente el diagrama de fases de la aleación. Posteriormente, se llevó una sección del lingote al proceso de solidificación rápida mediante tambor rotativo. Se manipularon las variables del proceso: la estabilidad del chorro, el diámetro de la boquilla, la distancia de la superficie de la boquilla al medio de enfriamiento, el tiempo de residencia del material fundido en el crisol, la velocidad del tambor giratorio y el ángulo del chorro, hasta obtener un microalambre con un diámetro de 160µm. Por último, se determinó que un control inadecuado de estos parámetros puede dar lugar a polvos, escamas o al bloqueo de la salida del crisol. Su uso potencial dentro de la escala micro-nano como analogía a elementos estructurales y conductores eléctricos, además de su uso actual como recubrimiento anticorrosivo. Palabras Clave: ZnAlAg alloy, Melt spinning process, Microwire, DSC analysis, Thermodynamic simulation

El presente trabajo muestra los resultados preliminares de una investigación relacionada del efecto de las adiciones de Se sobre las propiedades mecánicas y microestructurales de una aleación Serie ANSI AA (ISO) 319.0 colada en moldes metálicos de acero estructural ASTM A36. Fueron obtenidas barras cilíndricas 3.34 cm de diámetro y 20 cm de largo. Una de las barras fue obtenida sin adición de Se colada a 610 °C. Dos más con adición de Se coladas a 610 y 720°C. Los lingotes fueron maquinados para obtener probetas para ensayo mecánico a la tensión y dureza. También fue realizada su caracterización microestructural. La adición de Se disminuye ligeramente el valor de dureza respecto a la aleación sin adición de Se de 77.33 A 69.05 HRB. La temperatura de colado también afectó el valor de dureza en la aleación con adición de Se colada a 720°C, ya que presentó un valor de dureza de 65.07 HRB, debido cualitativamente a un incremento en el tamaño de las fases presentes en el material. La adición de Se y temperatura de colado modifico la dureza, resistencia mecánica a la compresión y a la tensión.

The degradation of steel used in the oil industry has become a serious problem due to the high costs associated with material loss from corrosion. Applying thin layers of corrosion-resistant material promises to be a viable alternative for extending the service life of pipelines. ERCuAl-A2 electrode claddings were applied to API X70 carbon steel using the MIG brazing process with direct current (DC) and pulsed current (P). The cladding was applied under three conditions: base material (BM) at room temperature, BM preheated to 120 °C, and Ni-buttered BM. Microhardness profiles and Charpy impact tests were performed on the MB and all cladding conditions. The API X70 carbon steel showed a microhardness value of 186.95 ± 11.17 Vickers, while the microhardness profiles of the ERCuAl A2 cladding showed values that differed in the intermetallic zone generated by the welding process. Likewise, the impact behavior of the base material and the applied claddings was ductile, except for conditions C2PF and C3PF, which showed a brittle–ductile behavior. The highest values of absorbed energy obtained from the tests were found in the conditions applied with DC, with values of approximately 50 MJm-3, due to the transfer mode of application of the cladding and/or the position in which the notch was made.