Influence of Cryomilling on Crystallite Size of Aluminum Powder and Spark Plasma Sintered Component

Abstract

The present investigation aims to develop nanocrystalline (NC) pure aluminum powders using cryomilling technique and manufacture bulk components using spark plasma sintering (SPS). The cryomilling was performed on pure Al powders for 2, 6, and 8 h. The cryomilled powders were then consolidated using SPS to produce bulk components. The particle morphology and crystallite size of the powders and the bulk SPS components were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the crystallite size of pure Al powders decreases with increased cryomilling time. The results also showed that the SPS at elevated temperatures resulted in a slight increase in crystallite size, however, the changes were insignificant. The mechanical properties of the bulk components were determined using a Vickers microhardness tester. The hardness of the cryomilled SPS component was determined to be three times higher than that of the unmilled SPS component. The mechanism for the reduction in crystallite size with increasing cryomilling time is discussed. This fundamental study provides an insight into the development of bulk nanomaterials with superior mechanical properties for automotive, aerospace, marine, and nuclear applications.

Manufacturing Bulk Nanocrystalline Al-3Mg Components Using Cryomilling and Spark Plasma Sintering

“…To minimize the grain coarsening for NC materials, the excess grain boundary energy needs to be stabilized without compromising the crystallite size of the materials. Recent studies have demonstrated that preferential doping of the high-energy grain boundaries with secondary phase dopants can reduce the interfacial energy at the grain boundaries [ 39 ]. It has also been demonstrated that the second phase material at the grain boundaries aids in pinning the grain boundaries, reducing their energy and their susceptibility to undergo grain coarsening [ 40 ].…”

Crystallization and Assembly-Driven Nanostructures for Energy, Electronics, Environment, and Emerging Applications

“…(iii) Controlling the crystalline components of inorganic materials attracts an intense scientific interest, in efforts to achieve optimization in crystallography, crystallization process (including dynamics), hierarchical morphology, nanostructure, nanopattern, or assembly-driven interfaces and composites. These changes largely contribute to the further enhancements in mechanical, ionic, electronic, and other functional behaviors of current-generation inorganic nanomaterials [ 3 , 4 , 5 ]. For example, Ultrasonic nanocrystalline surface modification represents a unique approach for mechanical impact-based surface deformation [ 3 ].…”

“…It has the potential towards gradient nanostructured surface layers, which can be impactful in the future generation of transportation, energy, medical, and chemical industries. Cryomilling and Spark Plasma Sintering are among other important approaches for enhancing the crystallites and properties of pure [ 4 ] and composite inorganics [ 5 ].…”