Three CoCrFeMnNi high-entropy alloys (HEAs) were produced by vacuum induction melting, induction melting under inert gas atmosphere, and melting under inert gas atmosphere followed by air exposure, respectively. The different manufacturing conditions for the three investigated alloys resulted in different levels and types of inclusions. The alloys melted under vacuum or inert gas contained Al2O3 inclusions formed by impurity Al, due to its high oxidation tendency. The molten alloy exposed in air showed an excessive oxidation. During oxidation of the molten alloy in air, impurity Al was initially oxidized, and fine MnCr2O4 inclusions were formed rather than pure Al2O3 inclusions. This difference was analyzed based on thermodynamic calculations. Specifically, the influence of impurity content on the inclusion characteristics was investigated for the three HEAs. Moreover, the inclusion characteristics were found to have an influence on mechanical properties of the alloys also. In air-exposed HEA, smaller inclusions were formed, resulting in a higher dislocation density at the matrix/inclusion interface and thus strengthening of the HEA. Thus, it is proposed that atmospheric conditions could be an important factor to control the inclusion characteristics and to form fine inclusion particles, which could improve the mechanical properties of HEAs.
Abstract. Forecasting ordering size and performance cost correctly in ordering of IT service project and initial stage of performance is very important factor not only to ordering body but also the company who performs the project. Middle standing IT service companies receive/perform public IT service projects, substituting large companies, after 2013 amendment of Software Industry Promotion Act. However, the business competence accumulated by middle standing IT service companies is relatively insufficient in project management ability, compared with large companies, and the style that project companies bear all risks of the project, such as Turn-key order in the market focused on large companies in the past, has great risk to ordering body, project company, and service beneficiaries in quality, costs, profit and delivery date. Currently, the market centered with middle standing IT service companies deteriorates the profitability of interested parties which makes IT service ecosystem, as an element of cost increase due to reduction of ordering size, low earnings yield, and increase of management expenses. Therefore, there"s necessity that the cost calculation and order style structure for IT service, which project companies should bear all the risk of project performance, should be improved. This treatise is going to analyze IT service market ecosystem and agreement, project performance style upon current IT service project cost calculation method based on SW lifespan process and suggest improvement method.
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