title: Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

authors: Bolzoni, Leandro

abstract: The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles.

text: Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles.

year: 2016

title: The textual expression of critical thinking in PhD discussions in applied linguistics

authors: Bruce, Ian

abstract: The purpose of this study was to identify the textual resources used to express critical thinking in the Discussion chapters or chapter sections of PhD theses from the discipline of Applied Linguistics. Five Discussions were manually analysed using the social genre/cognitive genre model of the author (Bruce, 2008a) as the analytical framework. Three generic elements, used integratively, were found to express critical evaluations as part of constructing an overall argument in the Discussion chapters examined. The first element was the recursive use of an organizing content schema (move pattern), described as: Point, Support, Evaluation. The second was the use of key coherence relations to make critical statements in the ‘Evaluation’ part of this content schema. The third element was the embedding within the critical statements of the metadiscourse devices of hedging and attitude markers (Hyland, 2005). While not providing a prescriptive approach to expressing critical evaluation in this genre, the findings offer an analytical lens through which novice writers may examine and develop awareness of the types of textual resource used to develop this important element of Discussions

text: The textual expression of critical thinking in PhD discussions in applied linguistics The purpose of this study was to identify the textual resources used to express critical thinking in the Discussion chapters or chapter sections of PhD theses from the discipline of Applied Linguistics. Five Discussions were manually analysed using the social genre/cognitive genre model of the author (Bruce, 2008a) as the analytical framework. Three generic elements, used integratively, were found to express critical evaluations as part of constructing an overall argument in the Discussion chapters examined. The first element was the recursive use of an organizing content schema (move pattern), described as: Point, Support, Evaluation. The second was the use of key coherence relations to make critical statements in the ‘Evaluation’ part of this content schema. The third element was the embedding within the critical statements of the metadiscourse devices of hedging and attitude markers (Hyland, 2005). While not providing a prescriptive approach to expressing critical evaluation in this genre, the findings offer an analytical lens through which novice writers may examine and develop awareness of the types of textual resource used to develop this important element of Discussions

year: 2018

title: In what ways do the perceptions of connectedness of Māori students in Alternative Education secondary schools affect their self-efficacy within the learning environment?

authors: Lemon, Katrina Suezanne

subjects: Alternative Education

abstract: This study has sought to identify connectedness for Māori students within the alternative-education, learning environment and the effect this has had on their self-efficacy. Alternative education in New Zealand is described as a place where second chance learners have access to education (Alternative Education National Body New Zealand, 2016). Generally, students are referred to alternative education due to becoming habitual truants, while other students are deemed as behaviourally-challenging, and are consequently excluded from school (Education Review Office, 2010; Ministry of Education, 2016a). A Critical Theory approach was employed guided by Kaupapa Māori methodology. Data was collected using the qualitative methods of focus-group interviews and one-to-one semi-structured interviews. An open-coded approach was adopted to analyse the data from the interview transcripts where themes were selected, and a summary reflection was written. 

Three distant themes were identified during the data analysis phase: Tāhuhu Kōrero – Kura; Alternative Education – Kura; and Alternative Education Teaching and Learning Approaches.  Within these themes sub-themes were explored: perceptions and experiences of primary and secondary school; Māori in mainstream education; the referring schools involvement; misconceptions; connection to the alternative-education, learning environment; centre and teacher practices; connection with Māori; and pathways, mana, and self-efficacy. An important aspect of this study was to seek to understand these students’ prior educational experiences before gathering their narratives on the alternative-education, learning environment. This was a strength of the study as the student narratives on their entire educational journey provided a depth of understanding for the researcher, and went towards explaining their disconnection, how it happened, and gave context to their referral to alternative education. 

The student narratives expressed a strong sense of connection to their primary-school, learning environment, however, a complete disconnection to their secondary-school, learning environment. Students expressed feeling discriminated against for being Māori, that there was no empathy or understanding given to their lived realities despite wanting to succeed at school. They felt that their teachers did not make an effort to connect with them describing a power imbalance between the teachers and themselves. The students felt that expectations were low, and that teachers could not be bothered to help them with their work. The student participants attributed this disconnection to the reason for their truancy and behavioural issues. The student narratives on the alternative-education, learning environment described an environment that was: whānau; where teachers worked at a connection and understood their learners; challenging them academically; where the teachers were highly committed to their students; where trust and respect was built; and where one size did not fit all - flexibility was exercised. Students felt that the alternative-education, learning environment provided them with career ambition, and academic confidence resulting in self-efficacy. 

This study provides student voice from a group that was overlooked within the Te Kotahitanga research project (Bishop, Berryman, Tiakiwai, & Richardson, 2003). To hear the voice of alternative education students is important in seeking to improve educational success and enjoyment for Māori priority learners. If we get to know and understand what works for these priority learners, we can then work towards making a difference for them within mainstream education. This study aims to identify the importance of connectedness for Māori students and how connectedness will positively affect Māori learners and their self-efficacy. 


Kia mau ki tō Māoritanga.
Hold fast to your Māori culture.

text: In what ways do the perceptions of connectedness of Māori students in Alternative Education secondary schools affect their self-efficacy within the learning environment? This study has sought to identify connectedness for Māori students within the alternative-education, learning environment and the effect this has had on their self-efficacy. Alternative education in New Zealand is described as a place where second chance learners have access to education (Alternative Education National Body New Zealand, 2016). Generally, students are referred to alternative education due to becoming habitual truants, while other students are deemed as behaviourally-challenging, and are consequently excluded from school (Education Review Office, 2010; Ministry of Education, 2016a). A Critical Theory approach was employed guided by Kaupapa Māori methodology. Data was collected using the qualitative methods of focus-group interviews and one-to-one semi-structured interviews. An open-coded approach was adopted to analyse the data from the interview transcripts where themes were selected, and a summary reflection was written. 

Three distant themes were identified during the data analysis phase: Tāhuhu Kōrero – Kura; Alternative Education – Kura; and Alternative Education Teaching and Learning Approaches.  Within these themes sub-themes were explored: perceptions and experiences of primary and secondary school; Māori in mainstream education; the referring schools involvement; misconceptions; connection to the alternative-education, learning environment; centre and teacher practices; connection with Māori; and pathways, mana, and self-efficacy. An important aspect of this study was to seek to understand these students’ prior educational experiences before gathering their narratives on the alternative-education, learning environment. This was a strength of the study as the student narratives on their entire educational journey provided a depth of understanding for the researcher, and went towards explaining their disconnection, how it happened, and gave context to their referral to alternative education. 

The student narratives expressed a strong sense of connection to their primary-school, learning environment, however, a complete disconnection to their secondary-school, learning environment. Students expressed feeling discriminated against for being Māori, that there was no empathy or understanding given to their lived realities despite wanting to succeed at school. They felt that their teachers did not make an effort to connect with them describing a power imbalance between the teachers and themselves. The students felt that expectations were low, and that teachers could not be bothered to help them with their work. The student participants attributed this disconnection to the reason for their truancy and behavioural issues. The student narratives on the alternative-education, learning environment described an environment that was: whānau; where teachers worked at a connection and understood their learners; challenging them academically; where the teachers were highly committed to their students; where trust and respect was built; and where one size did not fit all - flexibility was exercised. Students felt that the alternative-education, learning environment provided them with career ambition, and academic confidence resulting in self-efficacy. 

This study provides student voice from a group that was overlooked within the Te Kotahitanga research project (Bishop, Berryman, Tiakiwai, & Richardson, 2003). To hear the voice of alternative education students is important in seeking to improve educational success and enjoyment for Māori priority learners. If we get to know and understand what works for these priority learners, we can then work towards making a difference for them within mainstream education. This study aims to identify the importance of connectedness for Māori students and how connectedness will positively affect Māori learners and their self-efficacy. 


Kia mau ki tō Māoritanga.
Hold fast to your Māori culture.

year: 2017