title: Processing, microstructure and high strain rate behaviour of Ti-6Al-4V Alloy produced from a blended mixture using powder compact extrusion

authors: Singh, Ajit Pal

subjects: Blended powder metallurgy

abstract: Powder compact extrusion (PCE) is an innovative way of processing titanium and titanium alloys to produce good-quality material with a wide range of compositions, microstructures and mechanical properties. This paper explores PCE processing of Ti-6Al-4V alloy prepared from a blended powder mixture, containing elemental hydride-dehydride (HDH) titanium powder and master alloy (60Al-40V) powder. The warm pressed compacts of blended powders were sintered using a vacuum sintering furnace prior to β extrusion. The resulting material was used to measure the performance under high strain rate and tri-axial stress state using Charpy v-notch testing. A comparison was made of the microstructure after vacuum sintering and hot extrusion in addition to oxygen measurements to determine the degree of oxygen pickup during each processing stage. A comprehensive study of fracture surfaces in selected samples was carried out using optical microscopy and scanning electron microscopy. Based on the results, it is clear that certain samples picked up varying amounts of interstitial impurities during processing and as a consequence a significant number of micro-cracks were observed in lamellar type microstructures. The oxygen content of all as-extruded samples was between 0.34-0.44 wt.% with resultant impact toughness in the range of 10-14 J. The best impact toughness attained for the lowest oxygen as-extruded rods was 20% lower than the literature values for wrought material. In terms of fracture behaviour, ductile dimples, cleavage facets and cracks passing through lamellar structures were observed in all samples. However, the quantity of these fracture features varied significantly in each sample.

text: Processing, microstructure and high strain rate behaviour of Ti-6Al-4V Alloy produced from a blended mixture using powder compact extrusion Powder compact extrusion (PCE) is an innovative way of processing titanium and titanium alloys to produce good-quality material with a wide range of compositions, microstructures and mechanical properties. This paper explores PCE processing of Ti-6Al-4V alloy prepared from a blended powder mixture, containing elemental hydride-dehydride (HDH) titanium powder and master alloy (60Al-40V) powder. The warm pressed compacts of blended powders were sintered using a vacuum sintering furnace prior to β extrusion. The resulting material was used to measure the performance under high strain rate and tri-axial stress state using Charpy v-notch testing. A comparison was made of the microstructure after vacuum sintering and hot extrusion in addition to oxygen measurements to determine the degree of oxygen pickup during each processing stage. A comprehensive study of fracture surfaces in selected samples was carried out using optical microscopy and scanning electron microscopy. Based on the results, it is clear that certain samples picked up varying amounts of interstitial impurities during processing and as a consequence a significant number of micro-cracks were observed in lamellar type microstructures. The oxygen content of all as-extruded samples was between 0.34-0.44 wt.% with resultant impact toughness in the range of 10-14 J. The best impact toughness attained for the lowest oxygen as-extruded rods was 20% lower than the literature values for wrought material. In terms of fracture behaviour, ductile dimples, cleavage facets and cracks passing through lamellar structures were observed in all samples. However, the quantity of these fracture features varied significantly in each sample.

year: 2016

title: Nurturing the designerly thinking and design capabilities of five-year-olds: technology in the new entrant classroom

authors: Milne, Louise

subjects: technology

abstract: Technology is one of eight learning areas of the New Zealand national curriculum. It aims to develop a broad technological literacy through students participating in programmes in which the practice of technological development is experienced, as is knowledge informing practice, and students gain an understanding of technology as a domain in its own right. In New Zealand children begin school at 5 years of age and this paper describes a classroom research project during which these students design and then construct a photo frame. The inducement for this development arose from students needing to safely transport home and then display a class photograph. This provided the opportunity for developing technological knowledge and skills within a real and relevant context—two key drivers when working with young students (Ministry of Education 2007) [MoE]. The results of this project suggest that teaching technology to five-year-old students is achievable and a valuable addition to other learning opportunities provided in the new entrant classroom. Strategies are suggested that will enable students to successfully achieve their goals whilst gaining a simple understanding of the technological process. By making good use of these it is possible to create a worthwhile and imaginatively challenging activity that reflects the essence of the technology education curriculum.

text: Nurturing the designerly thinking and design capabilities of five-year-olds: technology in the new entrant classroom Technology is one of eight learning areas of the New Zealand national curriculum. It aims to develop a broad technological literacy through students participating in programmes in which the practice of technological development is experienced, as is knowledge informing practice, and students gain an understanding of technology as a domain in its own right. In New Zealand children begin school at 5 years of age and this paper describes a classroom research project during which these students design and then construct a photo frame. The inducement for this development arose from students needing to safely transport home and then display a class photograph. This provided the opportunity for developing technological knowledge and skills within a real and relevant context—two key drivers when working with young students (Ministry of Education 2007) [MoE]. The results of this project suggest that teaching technology to five-year-old students is achievable and a valuable addition to other learning opportunities provided in the new entrant classroom. Strategies are suggested that will enable students to successfully achieve their goals whilst gaining a simple understanding of the technological process. By making good use of these it is possible to create a worthwhile and imaginatively challenging activity that reflects the essence of the technology education curriculum.

year: 2013

title: Finding synergistic conservation values? Māori tikanga, science, resource management and law

authors: Simon, Katie

subjects: Indigenous knowledge

abstract: In this doctorate, I provide a balanced and collaborative approach to knowledge/value change between the contesting worldviews of indigenous knowledge and western science, termed 'synergistic'. My search for synergy is comparative and reconciliatory. This endeavours to overcome the popular pre-occupation with conflict and opposition. Rather, both difference and similarity are recognised. Through the comparison of such synergy, I argue that Māori development requires for its further advancement a focus not only on difference and conflict, but also on affinity and convergence.

My primary concern is to establish a better understanding of the synergistic, adaptive strategies or indigenous innovation of Māori kaitiaki, environmental stewards. I investigate conflicting and converging Māori and western scientific conservation and use values in Aotearoa/New Zealand  environmental governance and management regimes under the Resource Management Act 1991, with specific regard to indicator development. The balance of values were compared in ecological environmental governance, from five Aotearoa governmental authorities and three Māori river communities, utilising Māori and western social science methods. My focus on indicators pinpoints contesting knowledge/value change between the marginalisation of indigenous knowledge and dominance of western science. This seeks to highlight the potential viability of Māori kaitiakitanga, stewardship in global and national terms of sustainability.  

However, potential synergy is held back by a prevailing viewpoint of the indigenous worldview as backward, past-oriented and non-synergistic. An oppositional dogma predominates, which is a key problem to overcome. It spans world and national literature, resulting in considerable gaps in knowledge on synergy, conceptually, methodologically, empirically and analytically.  


This is addressed by an authoritative Māori synergistic standpoint from my own cultural lens and decolonised theorising, termed 'nuanced problem solving'. I articulate both worldviews in knowledge/value change through comparative, evolutionary, multi-dimensional, cross-cultural and inter-disciplinary research on synergy. My nuanced problem solving encapsulates the two main parts of the doctorate, whereby synergy is correlated between theory and social practice. Part one deals with value comparison in theory utilising high abstracted concepts and methods at the global level of environmental governance. Part two deals with value balance in social practice utilising medium abstracted and concrete empirical and analytical research at global, national, regional, district and cross-tribal levels of environmental governance. Potential synergy cross-cuts each part from high abstracted thought down and from the practical flax roots up. I argue that Māori advancement fluctuates between them. 

Drawing on cultural and theoretical leanings of the Māori synergistic standpoint, both a strong correlation with existing theory and expanded synergistic theorising was found. Due to the expansiveness of the research, these correlated findings only provide an embryonic understanding of potential synergy.

A postscript describes my other work on synergy with five external agencies concerning foreshore, lakeside, wastewater, land disposal and carbon marketing kaitiakitanga.  I argue that additional research on synergy is needed in order to further advance Māori.

text: Finding synergistic conservation values? Māori tikanga, science, resource management and law In this doctorate, I provide a balanced and collaborative approach to knowledge/value change between the contesting worldviews of indigenous knowledge and western science, termed 'synergistic'. My search for synergy is comparative and reconciliatory. This endeavours to overcome the popular pre-occupation with conflict and opposition. Rather, both difference and similarity are recognised. Through the comparison of such synergy, I argue that Māori development requires for its further advancement a focus not only on difference and conflict, but also on affinity and convergence.

My primary concern is to establish a better understanding of the synergistic, adaptive strategies or indigenous innovation of Māori kaitiaki, environmental stewards. I investigate conflicting and converging Māori and western scientific conservation and use values in Aotearoa/New Zealand  environmental governance and management regimes under the Resource Management Act 1991, with specific regard to indicator development. The balance of values were compared in ecological environmental governance, from five Aotearoa governmental authorities and three Māori river communities, utilising Māori and western social science methods. My focus on indicators pinpoints contesting knowledge/value change between the marginalisation of indigenous knowledge and dominance of western science. This seeks to highlight the potential viability of Māori kaitiakitanga, stewardship in global and national terms of sustainability.  

However, potential synergy is held back by a prevailing viewpoint of the indigenous worldview as backward, past-oriented and non-synergistic. An oppositional dogma predominates, which is a key problem to overcome. It spans world and national literature, resulting in considerable gaps in knowledge on synergy, conceptually, methodologically, empirically and analytically.  


This is addressed by an authoritative Māori synergistic standpoint from my own cultural lens and decolonised theorising, termed 'nuanced problem solving'. I articulate both worldviews in knowledge/value change through comparative, evolutionary, multi-dimensional, cross-cultural and inter-disciplinary research on synergy. My nuanced problem solving encapsulates the two main parts of the doctorate, whereby synergy is correlated between theory and social practice. Part one deals with value comparison in theory utilising high abstracted concepts and methods at the global level of environmental governance. Part two deals with value balance in social practice utilising medium abstracted and concrete empirical and analytical research at global, national, regional, district and cross-tribal levels of environmental governance. Potential synergy cross-cuts each part from high abstracted thought down and from the practical flax roots up. I argue that Māori advancement fluctuates between them. 

Drawing on cultural and theoretical leanings of the Māori synergistic standpoint, both a strong correlation with existing theory and expanded synergistic theorising was found. Due to the expansiveness of the research, these correlated findings only provide an embryonic understanding of potential synergy.

A postscript describes my other work on synergy with five external agencies concerning foreshore, lakeside, wastewater, land disposal and carbon marketing kaitiakitanga.  I argue that additional research on synergy is needed in order to further advance Māori.

year: 2007