title: Fabrication and characterization of novel low-cost ternary titanium alloys

authors: Paul, Manpreet

abstract: Titanium and titanium alloys are commonly used in applications such as aerospace and biomedical due to their excellent mechanical properties as well as biocompatibility. However, reduction of the cost in titanium alloys is still sought after aiming to expand the use of titanium to other consumer industries. By alloying β-stabilizer elements with titanium, superior mechanical properties can be obtained.

Novel ternary α + β Ti-xCu-xNb, Ti-xMn-xNb, Ti-xFe-xNb, Ti-xFe-xCu and Ti-xFe-xMn (x = 0.5, 1, 2, 3.5 and 5 in wt%) alloys were designed aiming to have enhanced mechanical properties compared to unalloyed titanium at lower cost. In this study, the alloys were fabricated via powder metallurgy (i.e. cold press and vacuum sintering) to lower the production costs. The microstructure and phase identification of the sintered alloys were performed using optical microscopy, scanning electron microscopy and X-ray diffraction. Mechanical properties were analysed through tensile testing and the Rockwell hardness test.

Experimental results showed that the mechanical properties (tensile and hardness) of all sintered ternary titanium alloys, proportionally increase with the amount of alloying elements added, nevertheless, ductility decreases.

High tensile properties were observed for the Ti-5Fe-5Cu alloy (due to the formation of the Ti2Cu phase, the strong β-stabilizer effects of Fe as well as a refined microstructure), in comparison to all the sintered ternary titanium alloys. Ti-5Fe-5Mn showed the highest hardness compared to all the sintered ternary titanium alloys, owing to the strong β-stabilizer effects of Fe and Mn (strong solid-solution strengthening effect), and an equiaxed microstructure. Cu and Nb as alloying elements added to Ti show high ductility compared to Fe and Mn, because of that the Ti-xCu-xNb alloy system showed higher elongations than the other alloy systems at the same total amount of alloying elements. It is worth mentioning that Ti-5Fe-5Cu was the only alloy to show comparable UTS and YS with Ti-6Al-4V, and Ti-5Fe-5Mn showed higher hardness compared to Ti-6Al-4V.

text: Fabrication and characterization of novel low-cost ternary titanium alloys Titanium and titanium alloys are commonly used in applications such as aerospace and biomedical due to their excellent mechanical properties as well as biocompatibility. However, reduction of the cost in titanium alloys is still sought after aiming to expand the use of titanium to other consumer industries. By alloying β-stabilizer elements with titanium, superior mechanical properties can be obtained.

Novel ternary α + β Ti-xCu-xNb, Ti-xMn-xNb, Ti-xFe-xNb, Ti-xFe-xCu and Ti-xFe-xMn (x = 0.5, 1, 2, 3.5 and 5 in wt%) alloys were designed aiming to have enhanced mechanical properties compared to unalloyed titanium at lower cost. In this study, the alloys were fabricated via powder metallurgy (i.e. cold press and vacuum sintering) to lower the production costs. The microstructure and phase identification of the sintered alloys were performed using optical microscopy, scanning electron microscopy and X-ray diffraction. Mechanical properties were analysed through tensile testing and the Rockwell hardness test.

Experimental results showed that the mechanical properties (tensile and hardness) of all sintered ternary titanium alloys, proportionally increase with the amount of alloying elements added, nevertheless, ductility decreases.

High tensile properties were observed for the Ti-5Fe-5Cu alloy (due to the formation of the Ti2Cu phase, the strong β-stabilizer effects of Fe as well as a refined microstructure), in comparison to all the sintered ternary titanium alloys. Ti-5Fe-5Mn showed the highest hardness compared to all the sintered ternary titanium alloys, owing to the strong β-stabilizer effects of Fe and Mn (strong solid-solution strengthening effect), and an equiaxed microstructure. Cu and Nb as alloying elements added to Ti show high ductility compared to Fe and Mn, because of that the Ti-xCu-xNb alloy system showed higher elongations than the other alloy systems at the same total amount of alloying elements. It is worth mentioning that Ti-5Fe-5Cu was the only alloy to show comparable UTS and YS with Ti-6Al-4V, and Ti-5Fe-5Mn showed higher hardness compared to Ti-6Al-4V.

year: 2021

title: Investigating the feasibility of using digital representations of work for performance assessment in engineering

authors: Williams, P. John

subjects: digital assessment

abstract: This paper reports on the results of a 3-year study conducted at the Centre for Schooling and Learning Technologies (CSaLT) at Edith Cowan University in collaboration with the Curriculum Council of Western Australia which concerns the potential to use digital technologies to represent the output from assessment tasks in the senior secondary course, Engineering Studies. The general aim of this study is to explore the potential of various digitally-based forms for external assessment for senior secondary courses in terms of manageability, cost, validity and reliability. The problem being addressed was the need to provide students with assessment opportunities in new courses, that are on one hand authentic, where many outcomes do not lend themselves to being assessed using pen and paper over a three hour period, while on the other hand being able to be reliably and manageably assessed by external examiners. That is, the external assessment for a course needs to accurately and reliably assess the outcomes without a huge increase in the cost of assessment. A computer managed examination was designed that consisted of a design task that was broken down into a number of timed activities. Students were paced through each activity, recording their input in the form of a portfolio. Input consisted of text, graphics through a camera, video and voice. The exam outputs were uploaded to a online repository. The students’ work was marked by external assessors using a standards based rubric that allowed the students work to be ranked though Rasch Modelling.

text: Investigating the feasibility of using digital representations of work for performance assessment in engineering This paper reports on the results of a 3-year study conducted at the Centre for Schooling and Learning Technologies (CSaLT) at Edith Cowan University in collaboration with the Curriculum Council of Western Australia which concerns the potential to use digital technologies to represent the output from assessment tasks in the senior secondary course, Engineering Studies. The general aim of this study is to explore the potential of various digitally-based forms for external assessment for senior secondary courses in terms of manageability, cost, validity and reliability. The problem being addressed was the need to provide students with assessment opportunities in new courses, that are on one hand authentic, where many outcomes do not lend themselves to being assessed using pen and paper over a three hour period, while on the other hand being able to be reliably and manageably assessed by external examiners. That is, the external assessment for a course needs to accurately and reliably assess the outcomes without a huge increase in the cost of assessment. A computer managed examination was designed that consisted of a design task that was broken down into a number of timed activities. Students were paced through each activity, recording their input in the form of a portfolio. Input consisted of text, graphics through a camera, video and voice. The exam outputs were uploaded to a online repository. The students’ work was marked by external assessors using a standards based rubric that allowed the students work to be ranked though Rasch Modelling.

year: 2012

title: Whitiwhiti Korero: Exploring the researchers' relationship in cross-cultural research

authors: Simpson, Mary Louisa

subjects: Aotearoa New Zealand

abstract: This paper explores the intercultural relationship between two New Zealanders and its influence in an unfolding cross-cultural research project involving kaumātua (Māori elders). Using a “critical incidents” approach, the authors undertake an exploration of the hyphen as the relationship in indigene-colonizer, bicultural collaboration. We show that for there to be political or structural development within cross-cultural research, personal commitment, and relationships are central to changing research and researcher practices.

text: Whitiwhiti Korero: Exploring the researchers' relationship in cross-cultural research This paper explores the intercultural relationship between two New Zealanders and its influence in an unfolding cross-cultural research project involving kaumātua (Māori elders). Using a “critical incidents” approach, the authors undertake an exploration of the hyphen as the relationship in indigene-colonizer, bicultural collaboration. We show that for there to be political or structural development within cross-cultural research, personal commitment, and relationships are central to changing research and researcher practices.

year: 2010