Commenced in January 2007
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Edition: International
Paper Count: 3

Search results for: Shae K. Kim

3 Inter-Filling of CaO and MgO Mixed Layer in Surface Behavior of Al-Mg Alloys Containing Al2Ca

Authors: Seong-Ho Ha, Young-Ok Yoon, Shae K. Kim

Abstract:

Oxide layer of normal Al-Mg alloy can be characterized by upper MgO and lower MgAl2O4 spinel. The formation of the MgO outmost layer occurs by the surface segregation of Mg in the initial oxidation. After then, the oxidation is proceeded with the formation of MgA12O4 spinel beneath the MgO. Growth of the oxide layer is accelerated by constant formation of MgA12O4 spinel. On the other hand, the oxidation resistance of Al-Mg alloys can be significantly improved simply by Mg+Al2Ca master alloy use as the Mg alloying element and such an improvement is attributed to the CaO/MgO mixed layer. Al-Mg alloy containing Al2Ca shows CaO as the upper layer and MgO as the lower one without MgA12O4 spinel. Such a dense oxide film acts as a protective layer. However, the CaO/MgO scale has the outmost MgO, partly, after a long time exposure to a harsh oxidation condition. The aim of this study is to investigate the inter-filling behaviour of CaO and MgO mixed layer in oxidation resistance mechanism of Al-Mg alloys containing Al2Ca. The process of outmost MgO layer formation will be clarified.

Keywords: Al-Mg alloy, Al2Ca, oxidation, MgO

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2 Grain Refinement of Al-7Si-0.4Mg Alloy by Combination of Al-Ti-B and Mg-Al2Ca Mater Alloys and Their Effects on Tensile Property

Authors: Young-Ok Yoon, Su-Yeon Lee, Seong-Ho Ha, Gil-Yong Yeom, Bong-Hwan Kim, Hyun-Kyu Lim, Shae K. Kim

Abstract:

Al-7Si-0.4Mg alloy (designated A356) is widely used in the automotive and aerospace industries as structural components due to an excellent combination of castability and mechanical properties. Grain refinement has a significant effect on the mechanical properties of castings, mainly since the distribution of secondary phase is changed. As a grain refiner, the Al-Ti-B master alloys containing TiAl3 and TiB2 particles have been widely used in Al foundries. The Mg loss and Mg based inclusion formation by the strong affinity of Mg to oxygen in the melting process of Mg contained alloys have been an issue. This can be significantly improved only by Mg+Al2Ca master alloy as an alloying element instead of pure Mg. Moreover, the eutectic Si modification and grain refinement is simultaneously obtained because Al2Ca behaves as Ca, a typical Si modifier. The present study is focused on the combined effects of Mg+Al2Ca and Al-Ti-B master alloys on the grain refiment of Al-7Si-0.4Mg alloy and their proper ratio for the optimum effect. The aim of this study, therefore, is to investigate the change of the microstructure in Al-7Si-0.4Mg alloy with different ratios of Ti and Al2Ca (detected Ca content) and their effects on the tensile property. The distribution and morphology of the secondary phases by the grain refinement will be discussed.

Keywords: Al-7Si-0.4Mg alloy, Al2Ca, Al-Ti-B alloy, grain refinement

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1 Creating Inclusive Workplace Practices to Support Individuals With Dyslexia Across the Employment Lifecycle: Perspectives From Employers, Managers, and Employees With Dyslexia

Authors: Shae Wissell, Leila Karimi, Tanya Serry, Lisa Furlong, Judith Hudson

Abstract:

Background: Employment and job security are key influences on health and wellbeing . Dyslexia affects approximately 1 in 10 individuals and is a lifelong disability . Little is known about the workplace practices through the lens of individuals with dyslexia and those who employ and manage dyslexic employees. Materials and Methods: Individual structured interviews were used to seek perspectives from two participant groups. The first study investigated the perspectives of 14 Australian adults with dyslexia in relation to their experiences, progression and performance management in the workplace. This data were analysed within the Job Demands-Resources Model of Burnout (JD-R Model) , which explores links between workplace characteristics and employee wellbeing. The second study explored the perspectives of four employers and managers about their experiences and self-efficacy managing dyslexic employees as well as their views on workplace inclusivity. Deductive content analysis was utilised to categorise and analyse the responses of participants . Results: Study 1: Of the 14 participants (adults with dyslexia) all reported experiencing challenges at different points throughout their employment, including a lack of awareness of dyslexia as a disability, exhaustion and discrimination. Many felt indecisive about whether to disclose their dyslexia in the workplace. A minority reported receiving positive, useful support from team members following disclosure. Study 2: Responses from employers and managers (n=4) indicated that although they personally had a some awareness of the challenges facing employees with dyslexia, they felt there was a lack of broader awareness and understanding of dyslexia as a disability, which could make it challenging for those with dyslexia, across their workplaces. They felt with the right reasonable adjustments in place those with dyslexia could complete work tasks to a high standard. By merging the results from these two studies, we were able to gain a better understanding of some of the workplace challenges faced by people with dyslexia and ways to improve organisational practices and inclusion. Although this study was conducted in a single state in Australia with a relatively small sample size, we present preliminary evidence demonstrating that employees with dyslexia face unique challenges related top their disability and this was often amplified by low levels of understanding about dyslexia from their peers. Additionally, employers and managers felt there was a lack of understanding of dyslexia as a disability and that workplaces could be doing more to create inclusive working environment. At present, dyslexia appears to be a risk factor to career satisfaction and success for many with the condition. To mitigate these difficulties, whole of organisation awareness training and the adoption of inclusive workplace practices could improve outcomes for employees with dyslexia. With inclusive, supportive, educated workplace environment, we would expect more employees with dyslexia to flourish, however further research particularly in an Australian setting is necessary to build on these finds, so we can garner a deeper and broader understanding of the issued faced by employers, managers and dyslexic employees.

Keywords: dyslexia, adults, disability, inclusion and diversity, workplaces, Australia, job demands resource model of burn out, employers, managers

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