Autor: ROBERTO MARTINEZ SANCHEZ

Wear behavior in Al2024–CNTs composites synthesized by mechanical alloying

JOSE LUIS BUENO ESCOBEDO IVANOVICH ESTRADA GUEL MARIO MIKI YOSHIDA LILIANA LICEA JIMENEZ ROBERTO MARTINEZ SANCHEZ (2012)

The wear behavior of the 2024 aluminum alloy and its composites was evaluated through a pin-on-disk system. For this purpose the aluminum alloy was reinforced by carbon nanotubes dispersion produced by milling process. The nanotubes dispersion was carried out using a high energy mill for a fixed milling time. Milled powders were cold consolidated, sintered and then microstructurally and mechanically evaluated. The wear behavior of the alloy and its composites was evaluated considering the different nanotube contents under several abrasive conditions. The composites with higher nanotube concentration (5.0 wt%) displayed an improved wear resistance in all cases evaluated in this work.

Artículo

Carbon nanotubes; Aluminum; Composites; Milling process; Abrasive wear; Pin-on-disc BIOLOGÍA Y QUÍMICA QUÍMICA

Microstructural and magnetic behavior of an equiatomic NiCoAlFe alloy prepared by mechanical alloying

JOSE MARTIN HERRERA RAMIREZ ROBERTO MARTINEZ SANCHEZ IVANOVICH ESTRADA GUEL JOSE ANDRES MATUTES AQUINO (2014)

Equiatomic NiCoAlFe powder alloys were synthesized by mechanical alloying. The microstructural evolution of the mechanically alloyed powders at different times was followed with X-ray diffraction and scanning electron microscopy. The as-mechanically alloyed powders were subjected to a rapid annealing treatment at 1273 K and 1473 K during 3 min in vacuum. X-ray diffraction studies show the structure of both, the as-mechanically alloyed and annealed powders, consisted in a mixture of nanocrystalline simple phases (FCC + BCC). Crystallite size, after annealing, still remained in nanoscale. Coercivity increased due to the decrease in crystallite size and because of the defects caused by mechanical alloying in the as-mechanically alloyed samples; then coercivity decreased due to the phenomenon of random magnetic anisotropy and tended to stabilize with longer alloying times. A similar behavior was observed in annealed samples at 1273 K. However, random magnetic anisotropy was not observed after annealing at 1473 K because crystals with larger sizes were produced, and a steady increase in coercivity was observed.

Artículo

BIOLOGÍA Y QUÍMICA

Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

ROBERTO MARTINEZ SANCHEZ (2015)

A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

Artículo

High entropy alloys; Mechanical alloying; Arc melting; Microstructure BIOLOGÍA Y QUÍMICA QUÍMICA

AlCoCuCrFeNiTi High Entropy Alloys Synthesized by Mechanical Alloying

CYNTHIA DEISY GOMEZ ESPARZA WILBER ANTUNEZ FLORES ROBERTO MARTINEZ SANCHEZ CARLOS ELIAS ORNELAS GUTIERREZ JOSE GERARDO CABAÑAS MORENO IVANOVICH ESTRADA GUEL JOSE MARTIN HERRERA RAMIREZ (2012)

Polvos elementales fueron mezclados y mecánicamente aleados para obtener tres aleaciones equiatómicas de alta entropía, NiCoAlFeCu, NiCoAlFeCuCr y NiCoAlFeCuCrTi. Los polvos fueron compactados y sinterizados a 1200 ºC. En las tres aleaciones sinerizadas, se observa la formación de al menos dos fases. En cada una está presente una fase rica en Cu, que se puede relacionar con la segregación de Cu reportada en las investigaciones realizadas por la ruta líquida. Los resultados de microdureza Vickers revelan que las fases ricas en Cu son las que presentan los valores mínimos de dureza.

Artículo

Aleación CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA QUÍMICA FÍSICA OTRAS