Mechanical Milling: a Top Down Approach for the Synthesis of Nanomaterials and Nanocomposites

TLDR

High‑energy ball milling is a widely used top‑down approach that overcomes the challenge of low‑cost, high‑yield synthesis of nanomaterials, enabling production of nanograins, nanoalloys, nanocomposites, and quasicrystalline materials through mechanical alloying of elemental or compound powders in an inert atmosphere. This review systematically examines the basic concepts, historical development, and applications of mechanical milling for synthesizing nanomaterials, nanocomposites, nanocarbons, and nano‑quasicrystalline materials. Mechanical alloying employs high‑energy ball milling of elemental powders in an inert atmosphere, where plastic deformation, cold‑welding, and fracture generate fine, dispersed alloy particles within a grain‑refined matrix. Mechanical milling has produced high‑yield Al/Ni/Mg/Cu nanoalloys, wear‑resistant spray coatings, oxide‑ and carbide‑strengthened Al alloys, and numerous other nanocomposites.

Abstract

Synthesis of nanomaterials by a simple, low cost and in high yield has been a great challenge since the very early development of nanoscience. Various bottom and top down approaches have been developed so far, for the commercial production of nanomaterials. Among all top down approaches, high energy ball milling, has been widely exploited for the synthesis of various nanomaterials, nanograins, nanoalloy, nanocomposites and nano -quasicrystalline materials. Mechanical alloying techniques have been utilized to produce amorphous and nanocrystalline alloys as well as metal/non-metal nanocomposite materials by milling and post annealing, of elemental or compound powders in an inert atmosphere. Mechanical alloying is a non-equilibrium processing technique in which different elemental powders are milled in an inert atmosphere to create one mixed powder with the same composition as the constituents. In high-energy ball milling, plastic deformation, cold-welding and fracture are predominant factors, in which the deformation leads to a change in particle shape, cold-welding leads to an increase in particle size and fracture leads to decrease in particle size resulting in the formation of fine dispersed alloying particles in the grain-refined soft matrix. By utilizing mechanical milling various kind of aluminium/ nickel/ magnesium/ copper based nanoalloys, wear resistant spray coatings, oxide and carbide strengthened aluminium alloys, and many other nanocomposites have been synthesized in very high yield. The mechanical milling has been utilized for the synthesis of nanomaterials either by milling and post annealing or by mechanical activation and then applying some other process on these activated materials. This review is a systematic view of the basic concept of mechanical milling, historical view and applications of mechanical milling in the synthesis of various nanomaterials, nanosomposites, nnaocarbons and nano quasicrystalline materials.