title: Microstructure and mechanical properties of large size Ti-43Al-9V-0.2Y alloy pancake produced by pack-forging

authors: Su, Yongjun

subjects: A. Titanium aluminide

abstract: A pancake of Ti-43Al-9V-0.2Y (at.%) alloy with dimensions of ϕ480 mm × 46 mm was fabricated by pack-forging with a thick reduction of 80%. The as-forged Ti-43Al-9V-0.2Y alloy pancake has a duplex (DP) microstructure, which is composed of B2/α₂/γ lamellar colonies and massive B2 and γ phase regions distributed along the boundaries between the lamellar colonies. Different microstructures were obtained by heat treatment of samples cut from the as-forged Ti-43Al-9V-0.2Y alloy pancake. A fully lamellar (FL) structure consisting of B2/α₂/γ lamellar colonies was obtained after the heat treatment of 1350 °C/8 h. Tensile test results exhibited that the yield strength (YS) and ultimate tensile strength (UTS) of the alloy with DP microstructure were decreased from 680.7 MPa to 834.3 MPa at room temperature to 589.5 MPa and 693.1 MPa at 700 °C, respectively, and the elongation (δ) of the alloy with DP microstructure was increased from 1.99% at room temperature to 12.12% at 700 °C; the elongation (δ) of the alloy with FL microstructure was increased from 1.52% at room temperature to 85.84% at 800 °C.

text: Microstructure and mechanical properties of large size Ti-43Al-9V-0.2Y alloy pancake produced by pack-forging A pancake of Ti-43Al-9V-0.2Y (at.%) alloy with dimensions of ϕ480 mm × 46 mm was fabricated by pack-forging with a thick reduction of 80%. The as-forged Ti-43Al-9V-0.2Y alloy pancake has a duplex (DP) microstructure, which is composed of B2/α₂/γ lamellar colonies and massive B2 and γ phase regions distributed along the boundaries between the lamellar colonies. Different microstructures were obtained by heat treatment of samples cut from the as-forged Ti-43Al-9V-0.2Y alloy pancake. A fully lamellar (FL) structure consisting of B2/α₂/γ lamellar colonies was obtained after the heat treatment of 1350 °C/8 h. Tensile test results exhibited that the yield strength (YS) and ultimate tensile strength (UTS) of the alloy with DP microstructure were decreased from 680.7 MPa to 834.3 MPa at room temperature to 589.5 MPa and 693.1 MPa at 700 °C, respectively, and the elongation (δ) of the alloy with DP microstructure was increased from 1.99% at room temperature to 12.12% at 700 °C; the elongation (δ) of the alloy with FL microstructure was increased from 1.52% at room temperature to 85.84% at 800 °C.

year: 2013

title: Time-varying risk premia in the term structure of interest rates in New Zealand

authors: Margaritis, Daimitri

subjects: New Zealand

abstract: An empirical analysis of the term structure of interest rates in New Zealand during the post-1985 financial liberalization period is presented. Particular emphasis is placed upon the effect of time-varying risk premia in the term structure equation. The risk premium is assumed to depend on the time-varying conditional variance of the excess holding yield. The results indicate that the expectations theory cannot be rejected at the short end of the term structure provided that account is taken of the volatility clustering in interest rate data. There is also support for the expectations theory in the term structure relationship between long-term and short-term interest rates. The results do not indicate excess over- or under-sensitivity of long rates to current short rates. Initial statistical evidence suggests that excess returns on long-term bonds can be explained by their lagged values and macroeconomic variables. However, this return predictability is removed once the effects of changing real and nominal uncertainty are accounted for in the term structure equation. The latter result suggests that a monetary policy of low and stable inflation can affect the risk characteristics of long-term bonds. The presence of varying real uncertainty in bond returns indicates that the slope of the yield curve may not be a reliable indicator for assessing inflationary pressures in the economy when compared to a situation where the variation in bond returns was solely driven by nominal uncertainty.

text: Time-varying risk premia in the term structure of interest rates in New Zealand An empirical analysis of the term structure of interest rates in New Zealand during the post-1985 financial liberalization period is presented. Particular emphasis is placed upon the effect of time-varying risk premia in the term structure equation. The risk premium is assumed to depend on the time-varying conditional variance of the excess holding yield. The results indicate that the expectations theory cannot be rejected at the short end of the term structure provided that account is taken of the volatility clustering in interest rate data. There is also support for the expectations theory in the term structure relationship between long-term and short-term interest rates. The results do not indicate excess over- or under-sensitivity of long rates to current short rates. Initial statistical evidence suggests that excess returns on long-term bonds can be explained by their lagged values and macroeconomic variables. However, this return predictability is removed once the effects of changing real and nominal uncertainty are accounted for in the term structure equation. The latter result suggests that a monetary policy of low and stable inflation can affect the risk characteristics of long-term bonds. The presence of varying real uncertainty in bond returns indicates that the slope of the yield curve may not be a reliable indicator for assessing inflationary pressures in the economy when compared to a situation where the variation in bond returns was solely driven by nominal uncertainty.

year: 1994

title: Kua Tupu Te Pā Harakeke: Developing Healthy Whānau Relationships

authors: Pihama, Leonie

abstract: We have opened this chapter with our ‘pēpeha’. Pēpeha are ways through which our people introduce ourselves. These vary from tribe to tribe. The essence of pēpeha is that they link us to our tribes and all associated with that. Our mountains, our rivers, our canoes, our ancestral lines. It links us to each other. It places us, as Māori, within a wider collective consciousness and relationships. It is important to highlight that the term ‘Māori’ is a term that brings us as tribal peoples together. It is a term that our people have chosen to use as a means of unifying ourselves in the wake of the arrival of our colonizers. Prior to colonization all identification was done through our whānau (extended family structure), hapū (subtribes) or iwi (tribes). The term Māori means to be ‘normal’ or ‘pure’, as such it is a fitting term for an Indigenous People. We have, however, also been active in maintaining our hapū and iwi identities and it is through pēpeha that we can culturally share that identity with each other. Our people have been doing this for generations. And in spite of colonization seeking to undermine our cultural identity, many of us continue to do this.

text: Kua Tupu Te Pā Harakeke: Developing Healthy Whānau Relationships We have opened this chapter with our ‘pēpeha’. Pēpeha are ways through which our people introduce ourselves. These vary from tribe to tribe. The essence of pēpeha is that they link us to our tribes and all associated with that. Our mountains, our rivers, our canoes, our ancestral lines. It links us to each other. It places us, as Māori, within a wider collective consciousness and relationships. It is important to highlight that the term ‘Māori’ is a term that brings us as tribal peoples together. It is a term that our people have chosen to use as a means of unifying ourselves in the wake of the arrival of our colonizers. Prior to colonization all identification was done through our whānau (extended family structure), hapū (subtribes) or iwi (tribes). The term Māori means to be ‘normal’ or ‘pure’, as such it is a fitting term for an Indigenous People. We have, however, also been active in maintaining our hapū and iwi identities and it is through pēpeha that we can culturally share that identity with each other. Our people have been doing this for generations. And in spite of colonization seeking to undermine our cultural identity, many of us continue to do this.

year: 2012