Author : Troy David Topping
Publisher :
ISBN 13 : 9781267663771
Total Pages : pages
Book Rating : 4.6/5 (637 download)
Book Synopsis Nanostructured Aluminum Alloys and Their Composites by : Troy David Topping
Download or read book Nanostructured Aluminum Alloys and Their Composites written by Troy David Topping and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminum alloys with nanocrystalline (NC) and ultra-fine grain (UFG) sizes are of interest because of their high strength - typically more than 30% stronger than conventionally processed alloys, with acceptable levels of tensile ductility - ranging from 3 - 15 %. By generating NC powders via mechanical milling in liquid nitrogen (cryomilling), a thermally stable UFG microstructure evolves during thermomechanical processing (TMP), which allows for large scale consolidation, and hence opportunity for basic studies. The constituents that stabilize the microstructure - dispersed oxides and nitrides - also contribute to the strength of the system. Careful examination of microstructures and stress-strain data generated for cryomilled pure Al and Al-Mg alloys, with various milling times and media allows strengthening mechanisms to be dissected, improving understanding of cryomilled Al alloys. Grain boundary (Hall-Petch), dispersion (Orowan), solid solution and dislocation hardening mechanisms are quantified based on experimentally developed UFG Al alloys crossing multiple investigations. Grain size variations in the materials are studied based on TMP routes, milling time and milling media. Dispersion strengthening is quantified and related to oxygen and nitrogen content in the consolidated materials. Solid solution strengthening via magnesium additions to the Al alloys is studied. And, dislocation hardening is investigated by cold rolling consolidated plates at room temperature. Additionally, the intentional incorporation of ceramic particulates, such as Al2O3 and B4C, provides the basis for analyzing systems using basic composite models. The effect of size and morphology of the particulates reinforcing the alloy to form the metal matrix composites (MMCs) is discussed in terms of specific surface area and a possible change in mechanism from load transfer to Orowan strengthening as the particulates approach nanometric scale.