title: Evaluation of reactive induction sintering as a manufacturing route for blended elemental Ti-5Al-2.5Fe alloy

authors: Jia, Mingtu

subjects: Science & Technology

abstract: This work focuses on gaining a better understanding of the feasibility of using reactive induction sintering to obtain the alloy Ti-5Al-2.5Fe using Ti, Al and Fe powders (i.e. via a blended elemental approach). For this, powder compacts were induction sintered under various temperature/time combinations like 700–1250 °C and isothermal holding of 0–15 min. Compositional homogeneity, microstructure evolution and mechanical properties of the sintered Ti-5Al-2.5Fe alloy were investigated. It was found that by increasing the sintering temperature and isothermal holding time, sintered Ti-5Al-2.5Fe components with a homogeneous chemical composition and a Widmanstätten microstructure can be produced. The tensile strength increases with the sintering temperature/time reaching comparable values to the wrought alloy; however the residual porosity has a significant impact on the ductility of the alloy. This study demonstrates that reactive induction sintering is suitable to shorten the production route of blended elemental Ti alloys to be used in non-critical applications where ductility is not the main requirement.

text: Evaluation of reactive induction sintering as a manufacturing route for blended elemental Ti-5Al-2.5Fe alloy This work focuses on gaining a better understanding of the feasibility of using reactive induction sintering to obtain the alloy Ti-5Al-2.5Fe using Ti, Al and Fe powders (i.e. via a blended elemental approach). For this, powder compacts were induction sintered under various temperature/time combinations like 700–1250 °C and isothermal holding of 0–15 min. Compositional homogeneity, microstructure evolution and mechanical properties of the sintered Ti-5Al-2.5Fe alloy were investigated. It was found that by increasing the sintering temperature and isothermal holding time, sintered Ti-5Al-2.5Fe components with a homogeneous chemical composition and a Widmanstätten microstructure can be produced. The tensile strength increases with the sintering temperature/time reaching comparable values to the wrought alloy; however the residual porosity has a significant impact on the ductility of the alloy. This study demonstrates that reactive induction sintering is suitable to shorten the production route of blended elemental Ti alloys to be used in non-critical applications where ductility is not the main requirement.

year: 2018

title: New Zealand pest fish species: Koi carp and Gambusia – fact sheet

authors: Tempero, Grant Wayne

abstract: New Zealand has a total of about 36 native freshwater fish species, and a further 22 (39% of all freshwater fish) have been introduced from overseas. Like all introduced species, they have some impact on New Zealand's native ecosystems, but some cause more problems than others.

text: New Zealand pest fish species: Koi carp and Gambusia – fact sheet New Zealand has a total of about 36 native freshwater fish species, and a further 22 (39% of all freshwater fish) have been introduced from overseas. Like all introduced species, they have some impact on New Zealand's native ecosystems, but some cause more problems than others.

year: 2015

title: Secondary school subject choice: an ethnographic study

authors: Darnell, Doreen Anne

abstract: This study of subject choice followed two groups of pupils through the decision-making process at two state, co-educational high schools in the North Island of New Zealand. The high schools were similar in size, location, ethnic composition and range of home background of pupils, but had differing option systems. 
At the end of their form two year, 53 children (27 boys, 26 girls) were interviewed at their respective primary or intermediate schools while they were considering the options offered to them in form three at one of the two high schools. The children were re-interviewed the following year at their respective high schools. A further 37 pupils (17 boys, 20 girls) were interviewed in form four at their respective high schools while they were choosing fifth form subjects and were re-interviewed the following year after they had experienced the subjects they had chosen. All children in the study were chosen by their teachers as being representative of the range of pupils at their schools, in terms of ability, ethnic origin and home background. 
In addition, parents of eight of the younger children were interviewed in their homes and 31 teachers, representing all the subjects offered to the children at the two high schools, were interviewed at their respective schools. 
Analysis of interview transcripts showed that pupils’ decisions were influenced by the structure of the option systems, the attitudes of parents and peers and by the overt and covert actions of teachers. Access to information was found to be a key component of decision making. Children’s and parents’ views about the school subjects showed a strong measure of agreement, but there was less agreement between children’ views and teachers’ views. 
A model of decision making was elicited from the data and case studies illustrated the range of pupils’ individual experience, in particular, the experience of Maori pupils identified as ‘winners’ and ‘losers’ in the school system.

text: Secondary school subject choice: an ethnographic study This study of subject choice followed two groups of pupils through the decision-making process at two state, co-educational high schools in the North Island of New Zealand. The high schools were similar in size, location, ethnic composition and range of home background of pupils, but had differing option systems. 
At the end of their form two year, 53 children (27 boys, 26 girls) were interviewed at their respective primary or intermediate schools while they were considering the options offered to them in form three at one of the two high schools. The children were re-interviewed the following year at their respective high schools. A further 37 pupils (17 boys, 20 girls) were interviewed in form four at their respective high schools while they were choosing fifth form subjects and were re-interviewed the following year after they had experienced the subjects they had chosen. All children in the study were chosen by their teachers as being representative of the range of pupils at their schools, in terms of ability, ethnic origin and home background. 
In addition, parents of eight of the younger children were interviewed in their homes and 31 teachers, representing all the subjects offered to the children at the two high schools, were interviewed at their respective schools. 
Analysis of interview transcripts showed that pupils’ decisions were influenced by the structure of the option systems, the attitudes of parents and peers and by the overt and covert actions of teachers. Access to information was found to be a key component of decision making. Children’s and parents’ views about the school subjects showed a strong measure of agreement, but there was less agreement between children’ views and teachers’ views. 
A model of decision making was elicited from the data and case studies illustrated the range of pupils’ individual experience, in particular, the experience of Maori pupils identified as ‘winners’ and ‘losers’ in the school system.

year: 1985