Mechanical Alloying of Nanocrystalline Materials and Nanocomposites

Abstract

Mechanical alloying is an effective method to synthesize nanocrystalline metal powders in the monolithic and composite states. The process involves repeated cold welding, fracturing and rewelding of powder particles in a high energy ball mill. Although originally developed to produce oxide dispersion strengthened superalloys, the technique has been later shown to be capable of producing a variety of metastable phases including nanocrystalline materials. The present article describes the synthesis of nanocrystalline materials and nanocomposites by mechanical alloying. The basic principles of the process, process parameters that affect the constitution and microstructure of the processed powders, and the mechanisms of alloying and grain refinement, including their consolidation to full density while retaining the nanostructures, are described. Methods to achieve the smallest possible grain size are then highlighted. Typical examples of the synthesis of nanocomposites containing a high volume fraction of nanometer-sized reinforcements in aluminum, and process optimization to achieve superplastic behavior in titanium-based nanocomposites are then discussed. The ubiquitous problem of powder contamination during milling and solutions to eliminate or minimize this are also mentioned.

On the possibility of applying severe plastic deformation by high pressure torsion for the manufacture of Al-Nb metal matrix composites

“…При этом в Al матрице синтезируются упрочняющие интерметаллидные (армирующие) фазы за счет их зарождения и роста, которые имеют меньшую деградацию при повышенных температурах [1]. Возможности изготовления алюмоматричных композитов по принципу in situ опробовано такими методами как, например, механическое легирование [2], разновидности быстрой кристаллизации [3], сварка трением с перемешиванием [4], интенсивная пластическая деформация (ИПД) [5] и др. Из перечисленных методов интенсивная пластическая деформация наиболее активно применяется для изготовления объемных наноструктурных металломатричных композитов [6].…”

Strategies to Achieve High Strength and Ductility of Pulsed Electrodeposited Nanocrystalline Co-Cu by Tuning the Deposition Parameters

“…The routes and parameters of materials processing will be key roles here. Currently, there are three possible methods to produce bulk tensile specimen of nanocrystalline materials, which are electrodeposition (ED) [1,2,11,12], severe plastic deformation (SPD) [5,13,14], and mechanical alloying and compaction (MA) [15,16]. In this paper, synthesis of bulk nanocrystalline Co-Cu through the pulsed electrodeposition (PED) will be conducted due to a simple route of production and a wide range of controlling process parameters.…”