title: High temperature deformation behavior of Ti–46Al–2Cr–4Nb–0.2Y alloy

authors: Kong, Fantao

subjects: Deformation

abstract: The hot deformation characteristics of cast and hot isostatically pressed Ti-46Al-2Cr-4Nb-0.2Y (at%) alloy in the temperature range of 1100-1250°C and strain rate range of 0.01-1.0s -1 using hot compression tests were studied. The processing map of the alloy at true strain of 0.5 was also developed on the basis of the dynamic materials model (DMM). The experimental results show that the flow stress decreases significantly with increasing deformation temperature and decreasing strain rate. Using the kinetic rate equation the stress exponent n and the apparent activation energy of deformation Q were determined as 4.47 and 400.4kJmol -1, respectively. The efficiency values of power dissipation of the domain at strain rate below 0.4s -1 show that the dynamic recrystallization occurring of γ phase in the alloy is easier in the wide deformation temperature range (1100-1250°C) due to low stacking fault energy. The fraction of new recrystallized grains increased with increasing the hot deformation temperature at a given strain rate. With the increasing of strain rate, the uniformity of microstructure was decreased. The domain defined by the temperature range of 1200-1230°C and the strain rate range of 0.01-0.05s -1 which corresponds to a peak efficiency of about 60% is the optimal deformation condition of the alloy. Based on the optimal deformation conditions, a cylindrical sample was near isothermally forged. The microstructure and shape of pancake by forging was in good agreement with the prediction of processing map.

text: High temperature deformation behavior of Ti–46Al–2Cr–4Nb–0.2Y alloy The hot deformation characteristics of cast and hot isostatically pressed Ti-46Al-2Cr-4Nb-0.2Y (at%) alloy in the temperature range of 1100-1250°C and strain rate range of 0.01-1.0s -1 using hot compression tests were studied. The processing map of the alloy at true strain of 0.5 was also developed on the basis of the dynamic materials model (DMM). The experimental results show that the flow stress decreases significantly with increasing deformation temperature and decreasing strain rate. Using the kinetic rate equation the stress exponent n and the apparent activation energy of deformation Q were determined as 4.47 and 400.4kJmol -1, respectively. The efficiency values of power dissipation of the domain at strain rate below 0.4s -1 show that the dynamic recrystallization occurring of γ phase in the alloy is easier in the wide deformation temperature range (1100-1250°C) due to low stacking fault energy. The fraction of new recrystallized grains increased with increasing the hot deformation temperature at a given strain rate. With the increasing of strain rate, the uniformity of microstructure was decreased. The domain defined by the temperature range of 1200-1230°C and the strain rate range of 0.01-0.05s -1 which corresponds to a peak efficiency of about 60% is the optimal deformation condition of the alloy. Based on the optimal deformation conditions, a cylindrical sample was near isothermally forged. The microstructure and shape of pancake by forging was in good agreement with the prediction of processing map.

year: 2012

title: Inequality within and between New Zealand urban areas

authors: Alimi, Omoniyi Babatunde

subjects: Income Inequality

abstract: A better understanding of the drivers of changes in the distribution of personal income continues to be of interest to academics, policy makers and the general public. While the focus has often been on the role of economic factors, socio-demographic factors play an important role as well. 

This thesis examines the socio-demographic determinants of changes in the distribution of income in New Zealand urban areas from 1986 to 2013, using data from the Censuses of Population and Dwellings. The thesis examines the role of changes in the age structure, immigration and patterns of educational assortative matching on the changes in the distribution of income over time and across areas. 

Multiple decomposition analyses are used to examine the composition and within-group distribution effects of ageing and immigration, while a counterfactual randomisation methodology is used to examine the effect of educational assortative matching. 

The results show that inequality has increased in New Zealand urban areas but there is spatial disparity in this trend and in its drivers.  Across areas, most of the rise in inequality was driven by increases in the metropolitan areas. Ageing of the population had a downward effect on inequality but widening of the age group-specific distributions has led to overall inequality growth. For immigration, increases in immigrant share have an inequality-increasing effect, but changes in the immigrant group-specific distribution of income are inequality-reducing in non-metropolitan areas and inequality-increasing in metropolitan areas.  With respect to the effect of patterns of partnering among male-female couples on inequality, it is shown that educational assortative matching has an inequality-increasing effect on the distribution of total income of couples. Moreover, spatial sorting on observable characteristics such as age, education and location has an inequality-increasing effect as well.

text: Inequality within and between New Zealand urban areas A better understanding of the drivers of changes in the distribution of personal income continues to be of interest to academics, policy makers and the general public. While the focus has often been on the role of economic factors, socio-demographic factors play an important role as well. 

This thesis examines the socio-demographic determinants of changes in the distribution of income in New Zealand urban areas from 1986 to 2013, using data from the Censuses of Population and Dwellings. The thesis examines the role of changes in the age structure, immigration and patterns of educational assortative matching on the changes in the distribution of income over time and across areas. 

Multiple decomposition analyses are used to examine the composition and within-group distribution effects of ageing and immigration, while a counterfactual randomisation methodology is used to examine the effect of educational assortative matching. 

The results show that inequality has increased in New Zealand urban areas but there is spatial disparity in this trend and in its drivers.  Across areas, most of the rise in inequality was driven by increases in the metropolitan areas. Ageing of the population had a downward effect on inequality but widening of the age group-specific distributions has led to overall inequality growth. For immigration, increases in immigrant share have an inequality-increasing effect, but changes in the immigrant group-specific distribution of income are inequality-reducing in non-metropolitan areas and inequality-increasing in metropolitan areas.  With respect to the effect of patterns of partnering among male-female couples on inequality, it is shown that educational assortative matching has an inequality-increasing effect on the distribution of total income of couples. Moreover, spatial sorting on observable characteristics such as age, education and location has an inequality-increasing effect as well.

year: 2019

title: Neoliberalism and racism in Aotearoa

authors: Rew, Nathan

abstract: Webinar Toru will engage with issues of racism, neoliberalism and what Graham Hingangaroa Smith has called ‘New Formations of Colonisation’. This webinar will provide an overview of neoliberalism and racism and how they intersect and impact upon Māori, Pacific Nations and ethnic minority groups in Aotearoa.

text: Neoliberalism and racism in Aotearoa Webinar Toru will engage with issues of racism, neoliberalism and what Graham Hingangaroa Smith has called ‘New Formations of Colonisation’. This webinar will provide an overview of neoliberalism and racism and how they intersect and impact upon Māori, Pacific Nations and ethnic minority groups in Aotearoa.

year: 2025