Influence of Cu content on microstructure and mechanical properties of thixoformed Al−Si−Cu−Mg alloys

The effects of Cu content on the microstructure and mechanical properties of thixoformed Al−6Si−хCu−0.3Mg (х= 3, 4, 5 and 6, mass fraction, %) alloys were studied. The samples were thixoformed at 50% liquid content and several of the samples were treated with the T6 heat treatment. The samples were then examined by optical microscopy (OM), scanning electron microscopy(SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis, as well as hardness and tensile tests. The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting. The results also reveal that as the Cu content in the alloy increases, the hardness and tensile strength of the thixoformed alloys also increase. The ultimate tensile strength, yield strength and elongation to fracture of the thixoformed heat-treated Al−6Si−3Cu−0.3Mg alloy are 298 MPa, 201 MPa and 4.5%, respectively, whereas the values of the thixoformed heat-treated alloy with high Cu content (6%) are 361 MPa, 274 MPa and 1.1%, respectively. The fracture of the thixoformed Al−6Si−3Cu−0.3Mg alloy shows a dimple rupture, whereas in the alloy that contains the highest Cu content (6%), a cleavage fracture is observed

The effects of mg addition on the microstructure and mechanical properties of Thixoformed Al-5%Si-Cu alloys

In this study, the effects of different amounts of magnesium (Mg) on the microstructures and tensile properties of thixoformed Al–5%Si–Cu alloys were investigated. Three different alloys containing various amounts of Mg (0.5, 0.8 and 1.2 wt%) were prepared through the cooling slope casting technique, before they were thixoformed using a compression press. Several of the thixoformed samples were then treated with a T6 heat treatment, that is, solution treatment at 525 C for 8 h, quenching in warm water at 60 C, followed by aging at 155 C for 4 h. All of the samples were then characterised by optical microscopy (OM), scanning electron microscopy (SEM) energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis as well as by tensile tests. The results revealed that magnesium was able to refine the size of a-Al globules and the eutectic silicon in the samples. It was also observed that a compact p-Al9FeMg3Si5 phase was formed when the magnesium content was 0.8 wt% and 1.2 wt%. The mechanical properties of the thixoformed alloys improved significantly after the T6 heat treatment. The highest attainment was recorded by the latter alloy (i.e. with 1.2 wt%Mg) with its ultimate tensile strength (UTS) as high as 306 MPa, yield strength (YS), 264 MPa, and elongation to fracture of 1.8%. The fracture of thixoformed alloy with a low Mg content (0.5 wt%) showed a combination of dimple and cleavage fracture, whereas in the alloy that contained the highest Mg content (1.2 wt%), cleavage fracture was observed

An overview of semisolid processing of aluminium alloys

Semisolid metal processing (SSM) or thixoforming is a new technology that offers several advantages over liquid processing and solid processing. This process utilizes semisolid behavior as well as reduces macrosegregation, porosity, and forming forces during shaping process. A lot of research work has been carried out by various researchers in order to exploit the potential of this process to produce different products especially for automotive industry. This paper will summarise the rheological behavior of aluminium alloys in semisolid slurries, thixoformability of modified aluminium alloys, the effect of feedstock production method on mechanical properties, and the importance of developing low-cost raw materials for semisolid processing

Patterns of injuries and illness among Malaysian athletes during the XVII Asian Games 2014

Although more Malaysians are taking part in International Multisport Games, these athletes well-being at such events have not been fully explored. The purpose of this study was to examine the pattern of injury and illness among Malaysian athletes during the XVII Asian Games 2014. Clinical and socio-demographic information of athletes diagnosed with injury or illness during the centralised training camp and at the Games were recorded in a standardised report form. Throughout the study period, 83 injuries and 64 illnesses were recorded from 276 athletes. Muscle strains and tears were the most common injury followed by ligamentous injury and soft tissues contusion. The number of injuries was highest among badminton players followed by hockey and rugby. Significantly higher incidence of injuries was observed among men than women hockey players. Athletes in individual events had higher proportion of more severe injury than those in team events. Respiratory tract infection was the most frequent illness diagnosed among athletes. Most injuries and illnesses diagnosed among athletes were minor and did not result in time away from participation. The incidence of injuries and illnesses among Malaysian athletes at the XVII Asian Games were comparable with those reported by previous authors. Injury and illness rate were influenced by gender and sports. Fortunately, majority of injuries and illnesses were minor and did not prevent athletes from participation

A technology readiness survey of UUM students on online learning applications

Technology changes the way of learning in the classroom.This study will be a significant endeavor in determine whether the level of acceptance of online learning application among students in the learning process.Universiti Utara Malaysia (UUM) students are the direct recipients of the service provided by the university on online learning applications.In this study there are some problem faced including whether online learning can reduce the use of resource that give effect to students.Generally use online learning among students will facilitate communication between each other, so how the use of online learning can help UUM students in the learning process.This can be carried out continuously to gain better relationship to the students as a whole by using technology readiness survey.The research will discuss the acceptance online learning applications provide by Universiti Utara Malaysia among students to identify the extent to which the use of online learning can save resource such as paper, time, money and others by using technology readiness survey.This study includes my methods for gathering information to investigate the readiness of Universiti Utara Malaysia students when using online learning application in learning process.The study further will explore the relationship between students and online learning based on technology readiness survey to achieve the goal as agents of green technology

Homogenous Dispersion And Interfacial Bonding Of Carbon Nanotube Reinforced With Aluminum Matrix Composite: A Review

Recent developments in the field of carbon nanotube (CNT) have attracted attentions on a new development of aluminum matrix composite (AMC). Homogenous dispersion and interfacial bonding of CNT/metal matrix are the two main problems yet to have sound solutions.In general, to ensure uniform dispersion, the overall process can be divided into three steps: preprocessing, mixing and post processing. This paper summarizes previousworks on solid and liquid processing techniques which some are more successful than others by looking at the improvement of the composite tensile strengths. On the other hand the interfacial bonding depends on the existance of Al4C3 phase and physical conditions of CNT. Both elements must be controlled for the optimized results. The review presented here would be used as references in the future works to fabricate higher strength CNT/aluminum composite

An empirical study of workers’ knowledge, attitudes, and practices (KAP) regarding safety risk across demographic factors and active BBS organizations: a factorial MANOVA approach

Construction is a high-risk sector, and construction workers engage in several activities that may expose them to grave risks. The conduct and qualities of workers may influence their awareness of workplace health and safety. Consequently, the purpose of this study was to investigate the knowledge, attitude, and practise (KAP) of employees regarding occupational safety in relation to individual characteristics and the interaction of the BBS programme at Malaysian construction sites. The one-way and two-way tests of multivariate analysis of variance were performed. Findings showed significant disparities in mean KAP scores across employee characteristics in relation to safety issues. Furthermore, the relationship between the BBS programme and personal characteristics was important in terms of employee safety attitudes and practises at the analysed construction sites. Enhancing safety (KAP) reduces employees’ divergent perceptions of workplace health and safety while simultaneously enhancing safety behaviour

Vehicular Ad Hoc Networks

(First paragraph) Vehicular ad hoc networks (VANETs) have recently been proposed as one of the promising ad hoc networking techniques that can provide both drivers and passengers with a safe and enjoyable driving experience. VANETs can be used for many applications with vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. In the United States, motor vehicle traffic crashes are the leading cause of death for all motorists between two and thirty-four years of age. In 2009, the National Highway Traffic Safety Administration (NHTSA) reported that 33,808 people were killed in motor vehicle traffic crashes. The US Department of Transportation (US-DOT) estimates that over half of all congestion events are caused by highway incidents rather than by rush-hour traffic in big cities. The US-DOT also notes that in a single year, congested highways due to traffic incidents cost over $75 billion in lost worker productivity and over 8.4 billion gallons of fuel. Some of the significant applications of VANETs are road safety applications including collision and other safety warning systems, driver convenience and information systems, and, in the future, intelligent traffic management systems

Thermodynamic modelling of Al-Si-Cu alloys for semisolid processing

Thixoforming is a new method in producing near net shape products which conducted in semisolid condition. This process can reduce macrosegregation, porosity and used low forming forces. Currently there are severals garde of aluminium alloys such as A319, A356 and A357 used in semi-solid metal processing. Therefore there is a demand to widen another grade of aluminium alloys specially tailored for semisolid metal processing. This study discusses the thermodynamic modelling to predict changes in the properties of aluminium alloy A319 expecially when the percentage content of alloying elements such as copper, manganese and iron is varies in order to fulfill the criteria of semisolid metal processing. The termodynamic modelling shows that the solidification temperature decreases from 130 to 113 celcius while the eutectic temperature increase from 510 to 515 celcius when the percentage of copper, mangan and ferum contents is increased. The liquid fraction sensitivity is reduced from 0.017 to 0.007 and teh working window temperature is reduced from 26 to 26 celcius. The results indicate the suitability of these modified alloys as a potential material for semisolid processing