Studies on grain refinement and alloying additions on the microstructure and mechanical properties of Mg-8Zn-4Al alloy

MAGNESIUM ALLOYS have strong potential for weight reduction in a wide range of technical applications because of their low density compared to other structural metallic materials. Therefore, an extensive growth of magnesium alloys usage in the automobile sector is expected in the coming years to enhance the fuel efficiency through mass reduction. The drawback associated with the use of commercially cheaper Mg-Al based alloys, such as AZ91, AM60 and AM50 are their inferior creep properties above 100ºC due to the presence of discontinuous Mg17A112 phases at the grain boundaries. Although rare earth-based magnesium alloys show better mechanical properties, it is not economically viable to use these alloys in auto industries. Recently, many new Mg-Al based alloy systems have been developed for high temperature applications, which do not contain the Mg17Al12 phase. It has been proved that the addition of a high percentage of zinc (which depends upon the percentage of Al) to binary Mg-Al alloys also ensures the complete removal of the Mg17Al12 phase and hence exhibits superior high temperature properties.ZA84 alloy is one such system, which has 8%Zn in it (Mg-8Zn-4Al-0.2Mn, all are in wt %) and shows superior creep resistance compared to AZ and AM series alloys. These alloys are mostly used in die casting industries. However, there are certain large and heavy components, made up of this alloy by sand castings that show lower mechanical properties because of their coarse microstructure. Moreover, further improvement in their high temperature behaviour through microstructural modification is also an essential task to make this alloy suitable for the replacement of high strength aluminium alloys used in automobile industry. Grain refinement is an effective way to improve the tensile behaviour of engineering alloys. In fact, grain refinement of Mg-Al based alloys is well documented in literature. However, there is no grain refiner commercially available in the market for Mg-Al alloys. It is also reported in the literature that the microstructure of AZ91 alloy is modified through the minor elemental additions such as Sb, Si, Sr, Ca, etc., which enhance its high temperature properties because of the formation of new stable intermetallics. The same strategy can be used with the ZA84 alloy system to improve its high temperature properties further without sacrificing the other properties. The primary objective of the present research work, “Studies on grain refinement and alloying additions on the microstructure and mechanical properties of Mg-8Zn-4Al alloy” is twofold: 1. To investigate the role of individual and combined additions of Sb and Ca on the microstructure and mechanical properties of ZA84 alloy. 2. To synthesis a novel Mg-1wt%Al4C3 master alloy for grain refinement of ZA84 alloy and investigate its effects on mechanical properties.

Grain refinement studies on Mg and Mg-Al based alloys

Demand on magnesium and its alloys is increased significantly in the automotive industry because of their great potential in reducing the weight of components, thus resulting in improvement in fuel efficiency of the vehicle. To date, most of Mg products have been fabricated by casting, especially, by die-casting because of its high productivity, suitable strength, acceptable quality & dimensional accuracy and the components produced through sand, gravity and low pressure die casting are small extent. In fact, higher solidification rate is possible only in high pressure die casting, which results in finer grain size. However, achieving high cooling rate in gravity casting using sand and permanent moulds is a difficult task, which ends with a coarser grain nature and exhibit poor mechanical properties, which is an important aspect of the performance in industrial applications. Grain refinement is technologically attractive because it generally does not adversely affect ductility and toughness, contrary to most other strengthening methods. Therefore formation of fine grain structure in these castings is crucial, in order to improve the mechanical properties of these cast components. Therefore, the present investigation is “GRAIN REFINEMENT STUDIES ON Mg AND Mg-Al BASED ALLOYS”. The primary objective of this present investigation is to study the effect of various grain refining inoculants (Al-4B, Al- 5TiB2 master alloys, Al4C3, Charcoal particles) on Pure Mg and Mg-Al alloys such as AZ31, AZ91 and study their grain refining mechanisms. The second objective of this work is to study the effect of superheating process on the grain size of AZ31, AZ91 Mg alloys with and without inoculants addition. In addition, to study the effect of grain refinement on the mechanical properties of Mg and Mg-Al alloys. The thesis is well organized with seven chapters and the details of the studies are given below in detail.

Information Dynamics and Knowledge Management in Science & Technology

This paper describes the current information dynamics and its effect in higher education and research in science and technology. Open access movement ,Institutional repositories ,Digital libraries,Knowledge gateways,Blogs,Wikis,and social bookmark tools have rapidly emerged on the web creating a new scenerio that radically changes the knowledge production process such as the creation of information,formats and sources of information,coding and processing ,accessing managing sharing and dissemination of information.The management of knowledge created by academia of Cochin University Of Science And Technology is examined in this challenging context of information dynamics.

Institutional Repositories: New Horizon of Science & Technology Knowledge Transactions

Today higher education system and R&D in science & Technology has undergone tremendous changes from the traditional class room learning system and scholarly communication. Huge volume of Academic output and scientific communications are coming in electronic format. Knowledge management is a key challenge in the current century .Due to the advancement of ICT, Open access movement, Scholarly communications, Institutional repositories, ontology, semantic web, web 2.0 etc has revolutionized knowledge transactions and knowledge management in the field of science & technology. Today higher education has moved into a stage where competitive advantage is gained not just through access of infonnation but more importantly from new Knowledge creations.This paper examines the role of institutional repository in knowledge transactions in current scenario of Higher education.

IR: Knowledge Creation, Knowledge Management and Knowledge Dissemination

Open access iiiovemerit and open source software movement plays an important role in creation of knowledge, knowledge management and knowledge dissemination. Scholarly communication and publishing are increasingly taking place in the electronic environment. With a growing proportion of the scholarly record now existing only in digital format, serious issues regarding access and preservation are being raised that are central to future scholarship. Institutional Repositories provide access to past. present and future scholarly literature and research documentation; ensures its preservation; assists users in discovery and use; and offers educational programs to enable users to develop lifelong literacy. This paper explores these aspects on how IR of Cochin University of Science & Technology supports scientific community for knowledge creation. knowledge Management, and knowledge dissemination.

Motion Segmentation And Meanshift Assisted Contour Refinement For Airborne Video

This paper presents methods for moving object detection in airborne video surveillance. The motion segmentation in the above scenario is usually difficult because of small size of the object, motion of camera, and inconsistency in detected object shape etc. Here we present a motion segmentation system for moving camera video, based on background subtraction. An adaptive background building is used to take advantage of creation of background based on most recent frame. Our proposed system suggests CPU efficient alternative for conventional batch processing based background subtraction systems. We further refine the segmented motion by meanshift based mode association.

Knowledge management and open access e-theses: Indian initiatives

This paper aims to describe recent developments in the services provided by Indian electronic thesis and dissertation (ETD) repositories. It seeks to explore the prospect of knowledge formation and diffusion in India and to discuss the potential of open access e-theses repositories for knowledge management.This study is based on literature review and content analysis of IndianETDrepository websites. Institutional repositories and electronic thesis and dissertation projects in India were identified through a literature survey as well as internet searching and browsing. The study examines the tools, type of contents, coverage and aims of Indian ETD repositories.The paper acknowledges the need for knowledge management for national development. It highlights the significance of an integrated platform for preserving, searching and retrieving Indian theses. It describes the features and functions of Indian ETD repositories.The paper provides insights into the characteristics of the national repository of ETDs of India, which encourage and support open access to publicly-funded research

Isp Knowledge Portal : A Resource Discovery Tool In Optics

The need to structure knowledge is as important now as it ever has been. This paper has tried to study the ISP knowledge portal to explore how knowledge on various resources and topics in photonics and related areas are organized in the knowledge portal of International School of Photonics, CUSAT. The study revealed that ISP knowledge portal is one of the best portals in the filed. It provides a model for building an effective knowledge portal in other fields

Knowledge Management: Creating Competitive Intelligence for the Future

In this knowledge era, the value of corporations, academic organizations and individuals is directly related to their knowledge and intellectual capital(IC). A newand potentially paradigm shift focus in the intersection between knowledge and intelligence is the recognition of the importance of understanding the intellectual capital of organizations. This paper explains how Cochin University of Science and Technology (CUSAT) is identifying and managing its intellectual capital for creating competitive advantage for the future. This paper also explores the different cost effective knowledge management strategies applied at CUSAT for managing its intellectual capital

Use of Online Information Resources for Knowledge Organisation in Library and Information Centres: A Case Study of CUSAT

The paper discusses the use of online information resources for organising knowledge in library and information centres in Cochin University of Science and Technology (CUSAT). The paper discusses the status and extent of automation in CUSAT library. The use of different online resources and the purposes for which these resources are being used, is explained in detail. Structured interview method was applied for collecting data. It was observed that 67 per cent users consult online resources for assisting knowledge organisation. Library of Congress catalogue is the widely used (100 per cent) online resource followed by OPAC of CUSAT and catalogue of British Library. The main purposes for using these resources are class number building and subject indexing

Design of a Knowledge-Based Geographic Information System

A GIS has been designed with limited Functionalities; but with a novel approach in Aits design. The spatial data model adopted in the design of KBGIS is the unlinked vector model. Each map entity is encoded separately in vector fonn, without referencing any of its neighbouring entities. Spatial relations, in other words, are not encoded. This approach is adequate for routine analysis of geographic data represented on a planar map, and their display (Pages 105-106). Even though spatial relations are not encoded explicitly, they can be extracted through the specially designed queries. This work was undertaken as an experiment to study the feasibility of developing a GIS using a knowledge base in place of a relational database. The source of input spatial data was accurate sheet maps that were manually digitised. Each identifiable geographic primitive was represented as a distinct object, with its spatial properties and attributes defined. Composite spatial objects, made up of primitive objects, were formulated, based on production rules defining such compositions. The facts and rules were then organised into a production system, using OPS5