Mai hē tātou e haka ‘ite nei ki te ŋāpoki: A collaborative story of indigenous knowledge in a school setting in Rapa Nui

This research explores the stories of indigenous educators in Rapa Nui, and their engagement with the development of Rapa Nui language and culture in the primary school curriculum. It is suggested that indigenous education in the island has promoted considerable agency in the development of national intercultural policies, emphasizing the resourcefulness they have had in doing so. This will be discussed in the case of an indigenous education programme that has been worked through to allow Rapa Nui children to learn in their native language, focusing on the participation that school teachers, staff and parents have in this endeavour. Positioning myself as a non-indigenous researcher, I am interested in following up on concerns discussed by theorists of decolonization, as a response to Western determination of what constitutes research; particularly in indigenous communities. This concern is reflected in the question that the research addresses, namely how intercultural education in Rapa Nui may or may not allow a forum for indigenous children on the island to develop a culturally responsive education. The thesis narrates the conception and implementation of indigenous education in Rapa Nui in a school setting. The experience of the participants highlights the need to recognize the asymmetry that has characterized intercultural relations at school throughout the history of formal education in the island. Further, they point to a revitalizing concept of culture to create a curriculum based on the Rapa Nui knowledge tradition. By giving space to this knowledge, it in turn implies a challenge to the existing educational frameworks. Responsibility over language revitalization and enhancement of local knowledge has gradually been positioned in school, and reflection on this work highlights the need to develop strategies that involve the wider society (local and national) in creating a renewed space for indigenous knowledge

Control Upstream Austenite Grain Coarsening during Thin Slab Casting Direct Rolling (TSCDR) Process

Thin-slab cast direct-rolling (TSCDR) has become a major process for flat-rolled production. However, the elimination of slab reheating and limited number of thermomechanical deformation passes leave fewer opportunities for austenite grain refinement, resulting in some large grains persisting in the final microstructure. In order to achieve excellent ductile to brittle transition temperature (DBTT) and drop weight tear test (DWTT) properties in thicker gauge high-strength low-alloy products, it is necessary to control austenite grain coarsening prior to the onset of thermomechanical processing. This contribution proposes a suite of methods to refine the austenite grain from both theoretical and practical perspectives, including: increasing cooling rate during casting, liquid core reduction, increasing austenite nucleation sites during the delta-ferrite to austenite phase transformation, controlling holding furnace temperature and time to avoid austenite coarsening, and producing a new alloy with two-phase pinning to arrest grain coarsening. These methodologies can not only refine austenite grain size in the slab center, but also improve the slab homogeneity

Characterisation of strain-induced precipitation behaviour in microalloyed steels during thermomechanical controlled processing

The temperature at which thermomechanical controlled processing is undertaken strongly influences strain-induced precipitation (SIP) in microalloyed steels. In this study, the recrystallisation-precipitation-time-temperature curve was simulated to determine the full recrystallisation temperature, recrystallisation-stop temperature and the temperature where precipitation would occur at the shortest time. The calculated temperatures were verified by experimental testing for rolling between 1100 °C and 850 °C. On the basis of this a finishing deformation of 850 °C was chosen in order to maximise the precipitate number density formed in a fully unrecrystallised austenite. The orientation relationship between the SIP in austenite, and subsequent transformation to ferrite was identified by calculation from the coordinate transformation matrix, and by electron diffraction in the transmission electron microscope. The NbC formed as coherent/semi-coherent precipitates in the austenite, and remained coherent/semi-coherent in the ferrite, indicating a Kurdjumov-Sachs orientation relationship between the austenite and ferrite on transformation

Achieving homogeneity in a high-Fe β-Ti alloy laser-printed from blended elemental powders

Blended Elemental powders are an emerging alternative to pre-alloyed powders in metal additive manufacturing due to the wider range of alloys producible with them and the cost savings from not developing novel feedstock. In this study, in situ alloying and concurrent microstructure evolution during SLM are investigated by performing SLM on a BE Ti-185 powder while tracking the surface temperatures via Infra-red imaging and phase transformation via synchrotron X-ray Diffraction. We then performed post-mortem electron microscopy (Backscatter Electron imaging, Energy Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction) to further gain insight into microstructure development. We show that although exothermic mixing aids the melting process, laser melting results only in a mixture of alloyed and unmixed regions. Full alloying and thus a consistent microstructure is only achieved through further thermal cycling in the heat-affected zone