title: Microstructure and magnetic properties of nanostructured Al₂O₃-20vol%Fe₇₀Co₃₀ composite prepared by high energy mechanical milling

authors: Yusop, Masleeyati

subjects: ceramic-alloy composite

abstract: Al₂o₃-20vol%Fe₇₀Co₃₀ composite powders have been prepared by high energy ball milling a mixture of Al₂O₃ powder and Fe₇₀Co₃₀ alloy powder. The Fe₇₀Co₃₀ alloy powder was also prepared by mechanical alloying of Fe and Co powders using the same process. The effects of milling duration from 8 to 48 hours on microstructure and magnetic properties of the nanostructured composite powders have been studied by means of X-ray Diffractometry (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). It was found that the nanostructured composite powder particles with irregular shapes and Fe₇₀Co₃₀  alloy particles being embedded in them formed after 8 hours of milling. The average grain size of the Al₂O₃  matrix reduced drastically to less than 18nm after 16 hours of milling. On the other hand, the embedded alloy particles demonstrated almost unchanged average grain size in the range of 14-15nm. Magnetic properties of the powder compacts at room temperature were measured from hysteresis curves, and show strong dependence of the milling time, with the coercivity increasing from 67.1 up to 127.9kOe with increasing the milling time from 8 to 48 hours. The possible microstructural reasons for this dependence are discussed.

text: Microstructure and magnetic properties of nanostructured Al₂O₃-20vol%Fe₇₀Co₃₀ composite prepared by high energy mechanical milling Al₂o₃-20vol%Fe₇₀Co₃₀ composite powders have been prepared by high energy ball milling a mixture of Al₂O₃ powder and Fe₇₀Co₃₀ alloy powder. The Fe₇₀Co₃₀ alloy powder was also prepared by mechanical alloying of Fe and Co powders using the same process. The effects of milling duration from 8 to 48 hours on microstructure and magnetic properties of the nanostructured composite powders have been studied by means of X-ray Diffractometry (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). It was found that the nanostructured composite powder particles with irregular shapes and Fe₇₀Co₃₀  alloy particles being embedded in them formed after 8 hours of milling. The average grain size of the Al₂O₃  matrix reduced drastically to less than 18nm after 16 hours of milling. On the other hand, the embedded alloy particles demonstrated almost unchanged average grain size in the range of 14-15nm. Magnetic properties of the powder compacts at room temperature were measured from hysteresis curves, and show strong dependence of the milling time, with the coercivity increasing from 67.1 up to 127.9kOe with increasing the milling time from 8 to 48 hours. The possible microstructural reasons for this dependence are discussed.

year: 2009

title: Supporting Change-Aware Semantic Web Services

authors: Hinze, Annika

subjects: computer science

abstract: The Semantic Web is not only evolving into a provider of structured meaningful content and knowledge representation, but also into a provider of services. While most of these services support external users of the SW, we focus on a vital service within the SW – change management and adaptation. Change is a ubiquitous feature of the SW. In this paper, we propose a service architecture that embraces and utilises change to provide higher quality services. We introduce pilot implementations of two supporting services within this architecture.

text: Supporting Change-Aware Semantic Web Services The Semantic Web is not only evolving into a provider of structured meaningful content and knowledge representation, but also into a provider of services. While most of these services support external users of the SW, we focus on a vital service within the SW – change management and adaptation. Change is a ubiquitous feature of the SW. In this paper, we propose a service architecture that embraces and utilises change to provide higher quality services. We introduce pilot implementations of two supporting services within this architecture.

year: 2005

title: Editorial Introduction: The utility and futility of 'the nation' in histories of Aotearoa New Zealand.

authors: Coleborne, Catharine

subjects: New Zealand

abstract: An introduction is presented which discusses articles in the issue on New Zealand history, including one on interracial rape and sexual violence in the 1860s, one on postcolonial methodology and the historical concept of the British World, and one on Whanganui Māori claims to the Whanganui River.

text: Editorial Introduction: The utility and futility of 'the nation' in histories of Aotearoa New Zealand. An introduction is presented which discusses articles in the issue on New Zealand history, including one on interracial rape and sexual violence in the 1860s, one on postcolonial methodology and the historical concept of the British World, and one on Whanganui Māori claims to the Whanganui River.

year: 2011