title: Sintering behaviour and microstructures of Ti(Al,O)/Al₂O₃, Ti₃Al(O)/Al₂O₃ and TiAl(O)/Al₂O₃ in situ composites

authors: Cai, Z.H.

subjects: titanium

abstract: The sintering behaviour and microstructures of Ti(Al,O)/Al₂O₃, Ti₃Al(O)/Al₂O₃ and TiAl(O)/Al₂O₃ in situ composites produced using Al/TiO₂ composite powders have been studied. Ti(Al,O), Ti₃Al(O) and TiAl(O) represent α-Ti phase with dissolved Al and O, and Ti3Al and TiAl phases with dissolved O, respectively. The Al/TiO₂ composite powders were produced by high energy mechanical milling using Al and TiO₂ powders as the starting materials. It was found that the matrices of the composites became fully dense after sintering at 1550 °C, and the Al₂O₃ particles became fully sintered when the sintering temperature was increased to 1650 °C. The reactions between Al and TiO₂ which occur during heating the powder compacts to 1400 °C have little effect on the sintering of the composite powders. The Al₂O₃  particles in the composites become significantly coarsened during sintering at 1550 °C or above, and the coarsening rate of the Al₂O₃  particles increases in the order of Ti(Al,O)/Al₂O₃, Ti₃Al(O)/Al₂O₃ and TiAl/Al₂O₃ composites. This can be attributed to the decrease of the solidus temperature or melting points of the corresponding matrices. It is evident that in the initial stage of sintering, coarsening of the Al2O₃ particles occurs through coalescence. Hipping of the pre-sintered composites at 1300 °C with a pressure of 200 MPa without canning causes significant increase of the density and substantial further coarsening of the Al₂O₃ particles.

text: Sintering behaviour and microstructures of Ti(Al,O)/Al₂O₃, Ti₃Al(O)/Al₂O₃ and TiAl(O)/Al₂O₃ in situ composites The sintering behaviour and microstructures of Ti(Al,O)/Al₂O₃, Ti₃Al(O)/Al₂O₃ and TiAl(O)/Al₂O₃ in situ composites produced using Al/TiO₂ composite powders have been studied. Ti(Al,O), Ti₃Al(O) and TiAl(O) represent α-Ti phase with dissolved Al and O, and Ti3Al and TiAl phases with dissolved O, respectively. The Al/TiO₂ composite powders were produced by high energy mechanical milling using Al and TiO₂ powders as the starting materials. It was found that the matrices of the composites became fully dense after sintering at 1550 °C, and the Al₂O₃ particles became fully sintered when the sintering temperature was increased to 1650 °C. The reactions between Al and TiO₂ which occur during heating the powder compacts to 1400 °C have little effect on the sintering of the composite powders. The Al₂O₃  particles in the composites become significantly coarsened during sintering at 1550 °C or above, and the coarsening rate of the Al₂O₃  particles increases in the order of Ti(Al,O)/Al₂O₃, Ti₃Al(O)/Al₂O₃ and TiAl/Al₂O₃ composites. This can be attributed to the decrease of the solidus temperature or melting points of the corresponding matrices. It is evident that in the initial stage of sintering, coarsening of the Al2O₃ particles occurs through coalescence. Hipping of the pre-sintered composites at 1300 °C with a pressure of 200 MPa without canning causes significant increase of the density and substantial further coarsening of the Al₂O₃ particles.

year: 2006

title: Breaking down barriers in building teacher competence

authors: Bruce Ferguson, Pip

subjects: action research

abstract: Teachers may well be made, not born, and appointments to academic positions are often made without regard to the appointee’s prior experience or competence in teaching. In most New Zealand universities, compulsory teaching development is not required. Furthermore, enrolment in opportunities to help teachers to develop further, frequently do not attract high numbers. How can those of us who work in staff development work effectively with resistant staff? How can we ensure that what we offer has optimal value in diverse areas? This paper reflects on an action research process currently under way in a New Zealand university, which seeks to investigate the usefulness of current and new staff development initiatives and to maximise benefits to staff. The work was presented at the recent ALARA conference and reflections from this presentation are interspersed with accounts of the work. I have used italics to highlight the ‘process’ parts of the work as it was presented at ALARA.

text: Breaking down barriers in building teacher competence Teachers may well be made, not born, and appointments to academic positions are often made without regard to the appointee’s prior experience or competence in teaching. In most New Zealand universities, compulsory teaching development is not required. Furthermore, enrolment in opportunities to help teachers to develop further, frequently do not attract high numbers. How can those of us who work in staff development work effectively with resistant staff? How can we ensure that what we offer has optimal value in diverse areas? This paper reflects on an action research process currently under way in a New Zealand university, which seeks to investigate the usefulness of current and new staff development initiatives and to maximise benefits to staff. The work was presented at the recent ALARA conference and reflections from this presentation are interspersed with accounts of the work. I have used italics to highlight the ‘process’ parts of the work as it was presented at ALARA.

year: 2012

title: My responsibility in the face of mass extinction

authors: Gray-Sharp, Katarina

subjects: autoethnography

abstract: Extinction is the “irreversible condition of a species or other group of organisms having no living representatives in the wild, which follows the death of the last surviving individual of that species or group” (Hine and Martin 2015g, para. 1). Mass extinctions are extinctions of the greatest magnitude, occurring “when many diverse groups of organisms become extinct over short periods of time” (Condie 2011, 250). These “are not step-events but rather a step into a prolonged alternative global ecosystem state” (Hull 2015, R941). Five mass extinctions have previously been recorded. A sixth has begun. Humans are the cause of the latest episode.

This thesis develops an Indigenous, non-agential conception of responsibility for considering an ethical problem of wide consequence. Founded in mātauranga Māori and recalling the work of Emmanuel Levinas, it applies Kaupapa Māori autoethnography, narrative, and conceptual analyses alongside exegeses and a replication study. Investigations of responsibility across various positions are encountered: those found in place and polity, those made as visitor and the commanded, those gifted as inherited erudition and in the suffering-with. Now facing the last structural violence, what is my responsibility?

text: My responsibility in the face of mass extinction Extinction is the “irreversible condition of a species or other group of organisms having no living representatives in the wild, which follows the death of the last surviving individual of that species or group” (Hine and Martin 2015g, para. 1). Mass extinctions are extinctions of the greatest magnitude, occurring “when many diverse groups of organisms become extinct over short periods of time” (Condie 2011, 250). These “are not step-events but rather a step into a prolonged alternative global ecosystem state” (Hull 2015, R941). Five mass extinctions have previously been recorded. A sixth has begun. Humans are the cause of the latest episode.

This thesis develops an Indigenous, non-agential conception of responsibility for considering an ethical problem of wide consequence. Founded in mātauranga Māori and recalling the work of Emmanuel Levinas, it applies Kaupapa Māori autoethnography, narrative, and conceptual analyses alongside exegeses and a replication study. Investigations of responsibility across various positions are encountered: those found in place and polity, those made as visitor and the commanded, those gifted as inherited erudition and in the suffering-with. Now facing the last structural violence, what is my responsibility?

year: 2021