This thesis work is an experimental study of one type of Semi-Solid Metal casting (SSM) process which is called RheoMetalTM. This method is an efficient type of Rheocasting that creates a semi-solid slurry within 30 seconds that is used for a high pressure die casting machine. The purpose of using a slurry in a high pressure die casting machine is that the slurry has a higher viscosity due to its solid fraction. This makes the filling of the die cavity more laminar which reduces air entrapment in the casting. The difficulty with this type of casting is to control the process parameters to be able to insure a casting with desired properties. A few studies within RheoMetalTM has already been made but there is still a lack of knowledge of to what extent the process parameters affect the slurry. The goal in this work is to study how the different RheoMetalTM process parameters influence the primary α-Al solid fraction, shape and size. The process parameters that were studied in this work was the stirring rate, superheat and EEM amount. In this study, the so called growth layer has been removed to make more precise calculations of the primary α-Al. This work also aims to study how grain refinement affect the primary α-Al which is commonly used to improve the quality of castings. To be able to perform this study, both practical and theoretical work has been implemented. The casting process involved making of ladles and preparation of various equipment. The cast samples were then prepared by standard metallurgy procedure for optical analyse of the microstructure. A special etching reagent was used to analyse the microstructure in a microscope. The etching is called Weck’s reagent and its purpose is to differentiate the growth layer from the primary α-Al. The growth layer is formed during quenching and by excluding it, the calculation of the slurry’s primary α-Al becomes more precise. This is because the slurry is not quenched before it is inserted into the high pressure die casting machine, therefore no growth layer is formed. To analyse the cast samples, a special program was used to identify and to calculate the solid fraction, shape and size of the primary α-Al. The result from the calculations made by the program gave different tendencies when changing the EEM amount. The stirring rate showed a tendency to decrease the solid fraction and increase the shape factor. The superheat decreased the solid fraction and increased the shape factor. The grain refinement also decreased the solid fraction and increased the shape factor. There was no clear tendency showing that the equivalent circular diameter of the primary α-Al was affected by any of the parameters.

Assessment of trophic interactions between increasing populations of New Zealand fur seals (Arctocephalus forsteri) and fisheries in southern Australia is limited due to a lack of species specific demographic data and an understanding of the factors influencing population growth. To establish species specific demographic parameters a cross-sectional sample of New Zealand fur seal females (330) and males (100) were caught and individually-marked on Kangaroo Island, South Australia between 2000 and 2003. The seals were aged through examination of a postcanine tooth, which was removed from each animal to investigate age-specific life-history parameters. Annual formation of cementum layers was confirmed and accuracy in age estimation was determined by examination of teeth removed from individuals of known-age. Indirect methods of assessing reproductive maturity based on mammary teat characteristics indicated that females first gave birth between 4-8 years of age, with an average age at reproductive maturity of 5 years. Among reproductively mature females, age-specific reproductive rates increased rapidly between 4-7 years of age, reaching maximum rates of 70-81% between 8-13 years, and gradually decreased in older females. No females older than 22 years were recorded to pup. Age of first territory tenure in males ranged from 8-10 years. The oldest female and male were 25 and 19 years old, respectively. Post-weaning growth in females was monophasic, characterised by high growth rates in length and mass during the juvenile growth stage, followed by a gradual decline in growth rates after reproductive maturity. In contrast, growth in males was biphasic and displayed a secondary growth spurt in both length and mass, which coincided with sexual and social maturation, followed by a rapid decline in growth rates. Age-specific survival rates were high (0.823-0.953) among prime-age females (8-13 yrs of age) and declined in older females. Relative change in annual pup production was strongly correlated with reproductive rates of prime-age females and adult female survival between breeding seasons.