title: Transient liquid phase sintering of high density Transient liquid phase sintering of high density Fe₃Al using Fe and Fe₂Al₅/FeAl₂ powders Part 1: Experimentation and results

authors: Xydas, N.K.

subjects: sintering

abstract: High density Fe[sub 3]Al was produced through transient liquid phase sintering, using rapid heating rates of greater than 150 K min[sup -1] and a mixture of prealloyed and elemental powders. Prealloyed Fe[sub 2]Al[sub 5]/FeAl[sub 2] (50Fe/50Al, wt-%) powder was added to elemental iron powder in a ratio appropriate for producing an overall Fe[sub 3]Al (13•87 wt-%) ratio. The heating rate, sintering time, sintering temperature, green density and powder particle size were controlled during the study. Heating rate, sintering time and powder particle size had the most significant influence upon the sintered density of the compacts. The highest sintered density of 6•12 Mg m[sup -3] (92% of the theoretical density for Fe3Al) was achieved after 15 minutes of sintering at 1350°C, using a 250 K min[sup - 1] heating rate, 1-6 μm Fe powders and 5•66 μm alloy powders. SEM microscopy suggests that agglomerated Fe[sub 2]Al[sub 5]/ FeAl[sub 2] particles, which form a liquid during sintering, are responsible for a significant portion of the remaining porosity in high sintered density compacts, creating stable pores, larger than 100 μm diameter, after melting. High density was achieved by minimising the Kirkendall porosity formed during heating by unbalanced diffusion and solubility between the iron and Fe[sub 2]Al[sub 5]/FeAl[sub 2] components. The lower diffusion rate of aluminium in the prealloyed powder into the iron compared with elemental aluminium in iron, coupled with a fast heating rate, is expected to permit minimal iron-aluminium interdiffusion during heating so that when a liquid forms the aluminium dissolves in the iron to promote solidification at a lower aluminium content. This leads to a further reduction in porosity.

text: Transient liquid phase sintering of high density Transient liquid phase sintering of high density Fe₃Al using Fe and Fe₂Al₅/FeAl₂ powders Part 1: Experimentation and results High density Fe[sub 3]Al was produced through transient liquid phase sintering, using rapid heating rates of greater than 150 K min[sup -1] and a mixture of prealloyed and elemental powders. Prealloyed Fe[sub 2]Al[sub 5]/FeAl[sub 2] (50Fe/50Al, wt-%) powder was added to elemental iron powder in a ratio appropriate for producing an overall Fe[sub 3]Al (13•87 wt-%) ratio. The heating rate, sintering time, sintering temperature, green density and powder particle size were controlled during the study. Heating rate, sintering time and powder particle size had the most significant influence upon the sintered density of the compacts. The highest sintered density of 6•12 Mg m[sup -3] (92% of the theoretical density for Fe3Al) was achieved after 15 minutes of sintering at 1350°C, using a 250 K min[sup - 1] heating rate, 1-6 μm Fe powders and 5•66 μm alloy powders. SEM microscopy suggests that agglomerated Fe[sub 2]Al[sub 5]/ FeAl[sub 2] particles, which form a liquid during sintering, are responsible for a significant portion of the remaining porosity in high sintered density compacts, creating stable pores, larger than 100 μm diameter, after melting. High density was achieved by minimising the Kirkendall porosity formed during heating by unbalanced diffusion and solubility between the iron and Fe[sub 2]Al[sub 5]/FeAl[sub 2] components. The lower diffusion rate of aluminium in the prealloyed powder into the iron compared with elemental aluminium in iron, coupled with a fast heating rate, is expected to permit minimal iron-aluminium interdiffusion during heating so that when a liquid forms the aluminium dissolves in the iron to promote solidification at a lower aluminium content. This leads to a further reduction in porosity.

year: 2003-03

title: Swimming capabilities of stoats and the threat to inshore sanctuaries

authors: King, Carolyn M.

subjects: stoat

abstract: Stoats (Mustela erminea) are small carnivorous mammals which were introduced into New Zealand in the late 19th century, and have now become widespread invasive pests. Stoats have long been known to be capable of swimming to islands 1-1.5 km offshore. Islands further out have usually been assumed to be safe from invasion, therefore routine stoat monitoring on them has been considered un-necessary. Recent incursions, including a stoat found on Rangitoto Island (3 km offshore) in 2010, and another which was deduced to have reached Kapiti (5 km offshore) in 2009, along with distribution modelling and genetic studies, strongly support the proposition that stoats can swim much further than 1.5 km. Acceptance of this hypothesis depends on estimating the probability that such small animals could indeed swim so far unaided. This paper reports the results of a project designed to assist this debate by recording the paddling action, speed and minimal endurance of nine stoats observed (once each) swimming against an endless current in a flume at the Aquatic Research Centre, University of Waikato. Four of the five males and two of the four females could hold a position for at least five minutes against the maximum current available, averaging 1.36 ± 0.336 km/h. In steady swimming against a current of c. 1 km/hr, they all used a rapid quadripedal paddling action (averaging 250 strokes/min, stronger with the spread forepaws). Four of the nine swam strongly for >1 h, including one female who covered 1.8 km in nearly 2 h non- stop. Results from such artificial conditions cannot be conclusive, but support suggestions that wild stoats could indeed swim much further than 1.5 km, hence we conclude that the “risk zone” for  stoat reinvasions of inshore islands has been seriously under-estimated.

text: Swimming capabilities of stoats and the threat to inshore sanctuaries Stoats (Mustela erminea) are small carnivorous mammals which were introduced into New Zealand in the late 19th century, and have now become widespread invasive pests. Stoats have long been known to be capable of swimming to islands 1-1.5 km offshore. Islands further out have usually been assumed to be safe from invasion, therefore routine stoat monitoring on them has been considered un-necessary. Recent incursions, including a stoat found on Rangitoto Island (3 km offshore) in 2010, and another which was deduced to have reached Kapiti (5 km offshore) in 2009, along with distribution modelling and genetic studies, strongly support the proposition that stoats can swim much further than 1.5 km. Acceptance of this hypothesis depends on estimating the probability that such small animals could indeed swim so far unaided. This paper reports the results of a project designed to assist this debate by recording the paddling action, speed and minimal endurance of nine stoats observed (once each) swimming against an endless current in a flume at the Aquatic Research Centre, University of Waikato. Four of the five males and two of the four females could hold a position for at least five minutes against the maximum current available, averaging 1.36 ± 0.336 km/h. In steady swimming against a current of c. 1 km/hr, they all used a rapid quadripedal paddling action (averaging 250 strokes/min, stronger with the spread forepaws). Four of the nine swam strongly for >1 h, including one female who covered 1.8 km in nearly 2 h non- stop. Results from such artificial conditions cannot be conclusive, but support suggestions that wild stoats could indeed swim much further than 1.5 km, hence we conclude that the “risk zone” for  stoat reinvasions of inshore islands has been seriously under-estimated.

year: 2014

title: Colonial versus ancestral legacy: The assertion of culture and identity through public arts in Kirikiriroa/Hamilton

authors: Kiff, Shirin

subjects: Ethnography

abstract: This thesis is an ethnography of Hamilton. It focuses on the role of public arts as a cultural regeneration tool and their function in shaping the community(s) in Kirikiriroa/Hamilton through building a sense of place and identity. As a qualitative study, I conducted nine semi- structured interviews with public art artists, art advocates and residents to explore the relational context within which the development and transmission of meaning takes place, a process which is central to culture and identity. The primary purpose of the research interviews was to gain insight into the factors that motivate arts organisers and planners to direct valuable limited resources into public art projects and its observable outcomes. The second purpose of the interviews, conducted while walking to public artworks in the city centre with six participants, was to examine the effect of public art on the public.
My methods also include tracking press reviews, monitoring comments and posts on social media and institutional debates involving residents, artists, and public authorities concerning public arts. I also recorded data by taking photographs and recording field notes of my observations during and after the fieldwork process. Data gathering was also enhanced by the large-scale collection of written materials and resources, including public art publications and HCC policy documents. Taken together, these research methods allowed me to investigate whether Hamilton had achieved its goals in its cultural regeneration efforts. In my analysis, I discuss the role of public art and its association with place and consider how artworks may antagonise Māori-Pākehā relationships or otherwise emphasis residents’ sense of place.
Biculturalism and monoculturalism narratives appear to dominate public arts with the purpose of invoking either a colonial legacy or ancestral legacy while the politics of multiculturalism continue to jockey for place. Colonial legacy refers to the glorifying of colonial achievements while ancestral legacy in this context refers to Māori assertion of history, culture and identity. Particularly, in this research, ancestral legacy belonging to local hapū, Ngāti Wairere. Participants’ narratives reveal four overarching themes, 1) the publics’ resistance to the making of colonial places through public art, 2) Ngāti Wairere struggles to assert ancestral legacy through public arts, 3) the need for ethnically diverse artworks to create and maintain ethnically diverse places, and 4) a yearning for a collective identity represented through public arts. Hamilton’s public artworks are variously perceived as a superficial representation of Māori culture, identity and history, a reminder of a colonial binary discourse, the colonised versus the coloniser, an assertion of either a Māori ancestral legacy or a colonial legacy or, minimally, a nod to multiculturalism. Nevertheless, my research shows that participants engagement with these artworks reveal a yearning for a local collective identity that is still a work in progress.

text: Colonial versus ancestral legacy: The assertion of culture and identity through public arts in Kirikiriroa/Hamilton This thesis is an ethnography of Hamilton. It focuses on the role of public arts as a cultural regeneration tool and their function in shaping the community(s) in Kirikiriroa/Hamilton through building a sense of place and identity. As a qualitative study, I conducted nine semi- structured interviews with public art artists, art advocates and residents to explore the relational context within which the development and transmission of meaning takes place, a process which is central to culture and identity. The primary purpose of the research interviews was to gain insight into the factors that motivate arts organisers and planners to direct valuable limited resources into public art projects and its observable outcomes. The second purpose of the interviews, conducted while walking to public artworks in the city centre with six participants, was to examine the effect of public art on the public.
My methods also include tracking press reviews, monitoring comments and posts on social media and institutional debates involving residents, artists, and public authorities concerning public arts. I also recorded data by taking photographs and recording field notes of my observations during and after the fieldwork process. Data gathering was also enhanced by the large-scale collection of written materials and resources, including public art publications and HCC policy documents. Taken together, these research methods allowed me to investigate whether Hamilton had achieved its goals in its cultural regeneration efforts. In my analysis, I discuss the role of public art and its association with place and consider how artworks may antagonise Māori-Pākehā relationships or otherwise emphasis residents’ sense of place.
Biculturalism and monoculturalism narratives appear to dominate public arts with the purpose of invoking either a colonial legacy or ancestral legacy while the politics of multiculturalism continue to jockey for place. Colonial legacy refers to the glorifying of colonial achievements while ancestral legacy in this context refers to Māori assertion of history, culture and identity. Particularly, in this research, ancestral legacy belonging to local hapū, Ngāti Wairere. Participants’ narratives reveal four overarching themes, 1) the publics’ resistance to the making of colonial places through public art, 2) Ngāti Wairere struggles to assert ancestral legacy through public arts, 3) the need for ethnically diverse artworks to create and maintain ethnically diverse places, and 4) a yearning for a collective identity represented through public arts. Hamilton’s public artworks are variously perceived as a superficial representation of Māori culture, identity and history, a reminder of a colonial binary discourse, the colonised versus the coloniser, an assertion of either a Māori ancestral legacy or a colonial legacy or, minimally, a nod to multiculturalism. Nevertheless, my research shows that participants engagement with these artworks reveal a yearning for a local collective identity that is still a work in progress.

year: 2021