The mechanical behaviour of an ultrafine grained Ti-47Al-2Cr (at%) alloy in tension and compression and at different temperatures

A bulk ultrafine grained (UFG) Ti-47Al-2Cr (at%) alloy has been produced using a powder metallurgy process that combines high energy mechanical milling (HEMM) of a mixture of Ti, Al and Cr powders to produce a Ti/Al/Cr composite powder and hot isostatic pressing (HIP) of the composite powder compact. The purpose of the present study is to determine the mechanical behaviour of the alloy in tension and compression at room temperature (RT) and elevated temperatures, and also to compare the compression behaviour of the material with its tensile behaviour. It has been found that due to the residual pores, lack of full level interparticle bonding and high oxygen content (0.87wt%) in the consolidated samples, the UFG TiAl based alloy has a very low room temperature tensile fracture strength of 100 MPa and shows no tensile ductility. However these microstructural defects and high oxygen content have much less significant effect on the room temperature compressive mechanical properties, and the alloy shows a high compressive yield strength of 1410 MPa, and some ductility (plastic strain to fracture 4%). At elevated temperatures of 800oC and above, the alloy shows high tensile and compressive ductility as demonstrated by 75% tensile elongation to fracture and no cracking in upset forging with a height reduction of 50% at 900oC. The yield strength of the alloy at 900oC is 55 MPa in tension and 33 MPa in compression, both of which are lower than those of coarse grained TiAl based alloys with similar compositions at 900oC. This is due to a higher creep rate of the UFG alloy caused by the small grains. The good formability of the UFG TiAl based alloy as reflected by the lower critical temperature above which the alloy becomes highly formable indicates that the material can be used as a suitable precursor for secondary thermomechanical processing and super-plastic forming

Application of SCOPE-C to measure social inclusion among mental health services users in Hong Kong

This study describes the construction of the Chinese version of the Social and Communities Opportunities Profile (SCOPE), henceforth, the SCOPE-C, to measure social inclusion among mental health services users in Hong Kong. The SCOPE-C was developed based on concept-mapping and benchmarking of census questions. The questionnaire consisted of 56 items, went through a standardized linguistic validation process and was pilot tested with qualitative feedback from five users of mental health services. Altogether 168 Chinese service users were recruited through various NGO mental health services to have three times face-to-face interview between October 2013 and July 2014. Results indicated that items related to satisfaction with opportunities and perceived opportunities in various social domains had high consistency. Nearly all the Kappa statistics and Pearson correlation coefficients between the baseline and two rounds of re-test were significant. The SCOPE-C was considered a valid instrument for Hong Kong mental health user population

MC decomposition and boride formation in a next generation polycrystalline Ni based superalloy during isothermal exposure at 900 °C

Detailed microstructural characterisation of phases present in a next generation polycrystalline Ni based superalloy after thermal exposure at 900 °C was carried out, focusing on carbides and borides. Metastable M5B3 precipitated after 32 h had a stoichiometry of (Cr0.7Mo0.2W0.1)5B3 with substitutions with Ni, Co, Nb and Ta. Fine M23C6 (a = 10.62 Å) was overgrown by metastable M5B3, as shown by rigorous TEM-SAD pattern investigation. The borides were eventually dominated by Mo rich M3B2, at the apparent expense of MC. Decomposition of MC was confirmed; it transformed sequentially to γ and then γ΄. The primary driving force for the MC decomposition was attributed to γ΄ precipitation, increasing its fraction to the thermodynamic equilibrium at 900 °C

Analysis and Development of Emergency Management Information System for Railway Systems in Taiwan

Railway is one of the most efficient, convenient, and comfortable ways with maximum mobility to meet people. Railway accidents or disasters often cause delays and service interruptions, resulting in operational and other loss. Despite many railway systems in Taiwan having a variety of monitoring systems for natural disasters, they still need an efficient platform for the emergency management of disasters and accidents since time and efficiency are the keys to emergency management. This study aims to fill in this gap by developing an emergency management information system for Railway Systems in Taiwan, i.e. “Railway Emergency Management Information System”, to support railway emergency management center and its sub-divisions in resource management, communication, messaging, and information sharing among different groups. The system includes many features that will improve communications between emergency management center and the mobile emergency management center to facilitate the progress of the disaster control units and dispatching at the disaster site. The study’s information system has been designated by local railway administration as the core system and starts trial since February 2012. Information requirement analysis, framework and design of the aforementioned information system will be discussed in this paper. It is hoped that the present study's information system research will help improve the emergency response of railway administration and provide safer rail transport service for the passengers