Solid State Precipitation: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Seth Imhoff, Los Alamos National Laboratory; Robert Hackenberg, Los Alamos National Laboratory; Gregory Thompson, University of Alabama

Tuesday 6:00 PM
February 28, 2017
Room: Hall B1
Location: San Diego Convention Ctr

Session Chair: Seth Imhoff, Los Alamos National Laboratory

L-183: Analysis of Beta´ Cu4Ti Precipitation in Cu-Ti Alloys by Conventional and Diffusion-couple Methods: Felipe Hernandez-Santiago1; Victor Lopez-Hirata2; Maribel Sauced- Muñoz2; Pamela Hernandez-Duran2; Erika Avila-Davila3; 1Instituto Politecnico Nacional (ESIME); 2Instituto Politecnico Nacional (ESIQIE); 3Instituto Tecnologico de Pachuca
    An analysis of the Cu4T iprecipitation process was carried out in binary Cu-Ti alloys using the conventional method and subsequently employing a diffusion-couple based method, known as the Macroscopic-Gradient Method. The phase separation took place via the mechanism of spinodal decomposition at early stages of aging. The precipitation of the Cu4Ti phase preceeded to that of the Cu3Ti phase, which is formed by cellular precipitation. The highest hardness and fastest precipitation kinetics occurred at aging of 400 and 600 °C, respectively. In the case of the macroscopic gradient method, a diffusion couple of Cu-4 wt. Ti alloys and pure copper was prepared by a diffusion annealing. This analysis enabled to determine the equilibrium and coherent lines in this alloy system. The Gibbs-Thomson equation was verified for this type of precipitation.

L-184: Carbide Precipitation in a Low-alloy Ferritic Steel: Maribel Saucedo-Muñoz1; Victor Lopez-Hirata1; Rodrigo Gomez-Martinez1; Arturo Ortiz-Mariscal1; Jose Villegas-Cardenas2; Jorge Gonzalez-Velazquez1; 1Instituto Politecnico Nacional (ESIQIE); 2Universidad Politecnica (Valle de México)
    The precipitation evolution was studied during aging of 2.25Cr -1Mo steel at 550 °C. The as-received steel was aged in two different ways: the first one was the a continuous isothermal treatment at 550°C for times up to 2000 h and the second aging was performed using isothermal aging cycles which consisted of aging at 550°C for 60 min and then water quenched at room temperature. M23C6 and M6C precipitation occurred intragranular and intergranular in both types of aging. The coarsening of the carbides was observed to occur with the increase in aging time. Nevertheless, the growth kinetics coarsening was faster in the case of isothermal aging cycles. The hardness decreased with aging time in both cases; however, it occurred in a shorter aging time for the cyclic aging. Nanoindentation tests indicated the increase of ductility as the aging time increased.

L-185: Nanocomposites Ti/B/TiO2 by Mechanical Alloy Synthesis: Diana Jaramillo1; 1Centro de Investigacion y Desarrollo Tecnológico en Electroquimica
    The TiB2 cermet material, composed of a ceramic element (Boron) and a metallic (Titanium) it has properties as: hard wear resistant, relatively high fracture toughness, good electrical conductivity and excellent chemical resistance. These properties and characteristics depend of reagents nature, powders purity, and synthesis technique. Being the mechanical alloying an efficient technique for composites synthesis, this because is a simple and inexpensive processing method. Is a recently solid-state powder processing techniques involving repeated welding, fracturing and rewelding of power particles in high-energy ball milling, with few variables, as: powders/ball ratio, rate and time grinding, process control agent, mill. In this work we focus the TiB2 synthesis and its formation and evolution of TiB2 phase. This evolution could be by the effect of oxidation-reduction reaction occurred among TiO2, TiB2, Ti, and B by high-energy milling; opposed to the Ti/B mix, where the formation of TiB2 is slow and inefficient