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: A classic case of test envy in sex offender risk assessment

authors: Boer, Douglas Pieter

subjects: sex offender

abstract: The SORAG, SVR-20, VRS-S0, STATIC99, SONAR, STABLE (see below for references), and other relatively similar risk prediction tools (RSVPTs) are just a few of the currently available risk assessment measures designed for use with sexual offenders. These instruments all purport to do a similar job – providing estimates of likelihood to recidivate – and most of the associated authors claim that their test, or their type of test, does a better job at risk assessment than the competition. This same debate exists among the experts of risk assessment for non-sexual violent offenders and the discussion from this paper can be extended to risk assessment in general.

text: A classic case of test envy in sex offender risk assessment The SORAG, SVR-20, VRS-S0, STATIC99, SONAR, STABLE (see below for references), and other relatively similar risk prediction tools (RSVPTs) are just a few of the currently available risk assessment measures designed for use with sexual offenders. These instruments all purport to do a similar job – providing estimates of likelihood to recidivate – and most of the associated authors claim that their test, or their type of test, does a better job at risk assessment than the competition. This same debate exists among the experts of risk assessment for non-sexual violent offenders and the discussion from this paper can be extended to risk assessment in general.

year: 2002-04

title: “It’s becoming part of their knowing”: a study of bicultural development in an early childhood teacher education setting in Aotearoa/New Zealand

authors: Ritchie, Jenny

abstract: This study is an exploration of the implementation of bicultural development within a university-based early childhood teacher education programme in Aotearoa/New Zealand, which can be considered to be a bicultural country (Walker, 1987, p. 221). Bicultural development is a process in line with obligations contained within the Te Tiriti o Waitangi/The Treaty of Waitangi, which are reflected within the New Zealand Ministry of Education’s Revised Statement of Desirable Objectives and Practices (Ministry of Education, 1996a) and the early childhood curriculum, Te Whāriki (Ministry of Education, 1996b). The study adopts a critical, transformative theoretical paradigm, and employed an eclectic and emergent qualitative methodological approach, that reflected aspects from ethnographic, narrative and grounded theory methodologies. Interviews with university lecturers, early childhood care and education teachers, and professional development facilitators within the early childhood field; observations within early childhood care and education centres; audio taping of university class discussions; samples of university student assignments; and a written survey of graduates of the university teacher education programme provide the sources of data for the study. Central to the methodological process is a commitment to ethical care for participants, which involves attentive accountability to the interpretations that they place on the material that they contribute to the study and to the overall theorising of the significance of the findings. 

Key research questions of the study were to define ‘bicultural development’ in the context of early childhood care and education in this country; to identify key components of the bicultural development implementation process employed within the university teacher early childhood education programme; to distinguish some useful ‘indicators’ of bicultural development within early childhood centres; and to consider the implications for the teacher education programme in terms of preparing graduates to facilitate bicultural development within their future work in early childhood education. 

A significant finding of the study was the identification of a range of strategies for implementing bicultural development in early childhood education teacher education and care and education settings. The key strategies include Tiriti-based partnership models of teaching whereby Māori and Pākehā work alongside each other, enabling the paralleling of Māori and Western perspectives within both university teacher education and early childhood care and education programmes. It was considered essential that universities employ Māori lecturers to enable Māori content within the teacher education programme to be adequately provisioned. Since there are few Māori educators employed in mainstream early childhood services, it was suggested that teachers might seek to employ a “whanaungatanga” approach. This involves the early childhood centre staff creating a climate and environment in which Māori families/whānau are comfortable to participate fully in programme planning, implementation, and evaluation, which will enable all children attending to access Māori perspectives alongside the Western curriculum content. This approach is consistent with Article Two of Te Tiriti o Waitangi, which guaranteed to Māori their tino rangatiratanga, or self-determination. 

An implication for management and staff of early childhood teacher education programmes in Aotearoa/New Zealand is the need to equip graduates with the knowledge bases and commitment that will enable them to implement bicultural development, ideally through adopting, a whanaungatanga approach. This involves facilitating teacher education students to move beyond the dysconscious racism (King, 1994) that is deeply embedded in mainstream Pākehā culture in this country, to the position where they are able to adopt a critical, transformative stance that is humble, respectful and responsive to cultural difference. This stance includes valuing the inclusion of te reo me ōna tikanga throughout early childhood programmes, in a partnership initiated by teachers, but one in which whānau Māori are then able to take the lead in determining the nature and application of Māori content.

text: “It’s becoming part of their knowing”: a study of bicultural development in an early childhood teacher education setting in Aotearoa/New Zealand This study is an exploration of the implementation of bicultural development within a university-based early childhood teacher education programme in Aotearoa/New Zealand, which can be considered to be a bicultural country (Walker, 1987, p. 221). Bicultural development is a process in line with obligations contained within the Te Tiriti o Waitangi/The Treaty of Waitangi, which are reflected within the New Zealand Ministry of Education’s Revised Statement of Desirable Objectives and Practices (Ministry of Education, 1996a) and the early childhood curriculum, Te Whāriki (Ministry of Education, 1996b). The study adopts a critical, transformative theoretical paradigm, and employed an eclectic and emergent qualitative methodological approach, that reflected aspects from ethnographic, narrative and grounded theory methodologies. Interviews with university lecturers, early childhood care and education teachers, and professional development facilitators within the early childhood field; observations within early childhood care and education centres; audio taping of university class discussions; samples of university student assignments; and a written survey of graduates of the university teacher education programme provide the sources of data for the study. Central to the methodological process is a commitment to ethical care for participants, which involves attentive accountability to the interpretations that they place on the material that they contribute to the study and to the overall theorising of the significance of the findings. 

Key research questions of the study were to define ‘bicultural development’ in the context of early childhood care and education in this country; to identify key components of the bicultural development implementation process employed within the university teacher early childhood education programme; to distinguish some useful ‘indicators’ of bicultural development within early childhood centres; and to consider the implications for the teacher education programme in terms of preparing graduates to facilitate bicultural development within their future work in early childhood education. 

A significant finding of the study was the identification of a range of strategies for implementing bicultural development in early childhood education teacher education and care and education settings. The key strategies include Tiriti-based partnership models of teaching whereby Māori and Pākehā work alongside each other, enabling the paralleling of Māori and Western perspectives within both university teacher education and early childhood care and education programmes. It was considered essential that universities employ Māori lecturers to enable Māori content within the teacher education programme to be adequately provisioned. Since there are few Māori educators employed in mainstream early childhood services, it was suggested that teachers might seek to employ a “whanaungatanga” approach. This involves the early childhood centre staff creating a climate and environment in which Māori families/whānau are comfortable to participate fully in programme planning, implementation, and evaluation, which will enable all children attending to access Māori perspectives alongside the Western curriculum content. This approach is consistent with Article Two of Te Tiriti o Waitangi, which guaranteed to Māori their tino rangatiratanga, or self-determination. 

An implication for management and staff of early childhood teacher education programmes in Aotearoa/New Zealand is the need to equip graduates with the knowledge bases and commitment that will enable them to implement bicultural development, ideally through adopting, a whanaungatanga approach. This involves facilitating teacher education students to move beyond the dysconscious racism (King, 1994) that is deeply embedded in mainstream Pākehā culture in this country, to the position where they are able to adopt a critical, transformative stance that is humble, respectful and responsive to cultural difference. This stance includes valuing the inclusion of te reo me ōna tikanga throughout early childhood programmes, in a partnership initiated by teachers, but one in which whānau Māori are then able to take the lead in determining the nature and application of Māori content.

year: 2002