Wear Behavior of Hot Forged NiTi Parts Produced by PM Technique

Pre-alloyed NiTi powders were pressed at 400 degrees C, sintered at 1250 degrees C for 2 h and then cooled down at the rate of 5 degrees C/min to room temperature inside oxygen-free furnace. Later these sintered parts were forged at similar to 1050 degrees C [(+/- 25 degrees C) (Forged.1: 15% and Forged.2: 30%)]. Wear behaviors of the un-forged and hot forged parts were investigated. Wear tests were carried out via a pin-on-disk wear testing device according to ASTM G132-96 standard. The wear tests were performed for various sliding distances (200 m, 400 m and 600 m) at the speed of 1.2 m/s and under different loads of 5 N, 10 N and 15 N. Vickers macro-hardness values were measured at HV2. The samples were analyzed via SEM, EDS and MAP to determine the microstructure. Wear losses, wear rates and friction coefficients were measured in detail. The results showed that the best values in terms of wear and friction coefficient were obtained for 30% hot forged sample which had a hardness value of 612 HV and a density of 5.94 g/cm(3).C1 [Aksoz, Sinan] Pamukkale Univ, Fac Technol, Dept Met & Mat Engn, Denizli, Turkey

Hardness Properties of AA2014-SiC MMCs

In this study, microstructure and hardness effects of cryogenic and ageing heat treatments applied to AA2014-SiC composites containing vol. 0.5, 1, 2 and 4% SiC reinforcing ratio have been investigated. SEM, EDS, XRD and MAP analyses have been used in the determination of microstructural properties. Macro hardness measurements have been implemented for the investigation of hardness effects. Through the dissolution and cryogenic processes applied, alloying elements such as Cu, which has a direct effect on the formation of secondary phase in the structure, can be homogeneously dispersed in the microstructure. It has been also found that there is a significant increase in the hardness level due to the applied cryogenic treatment. A significant homogenous distribution of alloys is obtained in the MAP analysis after the cryogenic process. This is the reason why the cryogenic cooling process can be working dynamically, especially in ageing applicable alloys.[GRAPHICS]

10 wt.% of Nickel Powder Processed by Equal Channel Angular Pressing

The aim of this study is to consolidate the Al-Ni powders using the equal channel angular pressing method in order to achieve improved structural and mechanical properties. Thus, both alloying ability at low temperature, as a result of consolidations of ultrafine grained alloy by equal channel angular pressing method, and the average grain size and grain boundary angle have been studied and the effect of Nickel has been investigated. Severe plastic deformation and consolidation process with 15 passes of equal channel angular pressing, having route C, have been carried out at 200 degrees C using pure aluminum and aluminum with 10 wt.% of nickel. Electron backscatter diffraction was used to obtain scanning electron microscopy images and to determine the average grain size and average grain boundary angle. Density measurements of samples have been carried out using the Archimedes principle and the microhardness distributions have been obtained using the HV 0.5 method

Reconceptualised family resemblance approach to nature of science in pre-service science teacher education

A recent framework on nature of science (NOS) is the Family Resemblance Approach (FRA). FRA presents NOS as a cognitive-epistemic and social-institutional system with a set of categories: aims and values, scientific methods, scientific practices, scientific knowledge and social-institutional aspects of science. Although FRA has been problematised philosophically and its implications for science education have been considered by science educators, its empirical adaptations in science education are limited. In order to illustrate the educational adaptations of FRA, we refer to Reconceptualised Family Resemblance Approach to Nature of Science or RFN. We present a study based on a funded pre-service science teacher education project whose aim was to design, implement and evaluate the impact of RFN strategies. Fifteen pre-service teachers participated in a 14-week teacher education intervention that infused RFN. A 70-item questionnaire was designed to investigate the outcomes of the teacher education intervention. Individual interviews with pre-service teachers were also conducted. Quantitative and qualitative data analysis suggest that the teacher education intervention had an overall significant impact on pre-service teachers’ views of NOS. The paper contributes to the understanding of how NOS can be incorporated in science teacher education using a new orientation to NOS based on FRA

Solid-liquid interfacial energy of neopentylglycol solid solution in equilibrium with neopentylglycol-(D) camphor eutectic liquid

The grain boundary groove shapes for equilibrated solid neopentylglycol (NPG) solution (NPG-3 mol% fl-camphor) in equilibrium with the NPG-DC eutectic liquid (NPG-36.1 mol% fl-camphor) have been directly observed using a horizontal linear temperature gradient apparatus. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient (E), solid-liquid interfacial energy (or) of NPG solid solution have been determined to be (7.5 +/- 0.7) x 10(-8) K m and (8.1 +/- 1.2) x 10(-3) J m(-2), respectively. The Gibbs-Thomson coefficient versus T-m Omega(1/3), where Omega is the volume per atom was also plotted by linear regression for some organic transparent materials and the average value of coefficient (tau) for nonmetallic materials was obtained to be 0.32 from graph of the Gibbs-Thomson coefficient versus T-m Omega(1/3). The grain boundary energy of solid NPG solution phase has been determined to be (14.6 +/- 2.3) x 10(-3) J m(-2) from the observed grain boundary groove shapes. The ratio of thermal conductivity of equilibrated eutectic liquid to thermal conductivity of solid NPG solution was also measured to be 0.80. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved

Solid-liquid interfacial energy of solid aminomethylpropanediol solution in equilibrium with aminomethylpropanediol-neopentylglycol-D camphor liquid

The grain boundary groove shapes for equilibrated solid aminomethylpropanediol solution, BCC (AMPD-42.8 mol% NPG-3 mol% DC) in equilibrium with the liquid (AMPD-7 mol% NPG-3 mol% DC) have been directly observed by using a horizontal linear temperature gradient apparatus. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient (Gamma), solid-liquid interfacial energy (sigma(SL)) of solid AMPD solution have been determined to be (5.20 +/- 0.52) x 10(-8) Km and (8.89 +/- 1.33) x 10(-3) J m(-2), respectively. The grain boundary energy of solid AMPD solution has been determined to be (17.12 +/- 2.73) x 10(-3) J m(-2) from the observed grain boundary groove shapes. The ratio of thermal conductivity of equilibrated liquid to thermal conductivity of solid AMPD solution has also been determined to be 0.35. (C) 2013 Elsevier B.V. All rights reserved

Reconceptualised family resemblance approach to nature of science in pre-service science teacher education

A recent framework on nature of science (NOS) is the Family Resemblance Approach (FRA). FRA presents NOS as a cognitive-epistemic and social-institutional system with a set of categories: aims and values, scientific methods, scientific practices, scientific knowledge and social-institutional aspects of science. Although FRA has been problematised philosophically and its implications for science education have been considered by science educators, its empirical adaptations in science education are limited. In order to illustrate the educational adaptations of FRA, we refer to Reconceptualised Family Resemblance Approach to Nature of Science or RFN. We present a study based on a funded pre-service science teacher education project whose aim was to design, implement and evaluate the impact of RFN strategies. Fifteen pre-service teachers participated in a 14-week teacher education intervention that infused RFN. A 70-item questionnaire was designed to investigate the outcomes of the teacher education intervention. Individual interviews with pre-service teachers were also conducted. Quantitative and qualitative data analysis suggest that the teacher education intervention had an overall significant impact on pre-service teachers’ views of NOS. The paper contributes to the understanding of how NOS can be incorporated in science teacher education using a new orientation to NOS based on FRA

Dependency of thermal conductivity on the temperature and composition of D-camphor in the neopentylglycol-D-camphor alloys

Dependencies of thermal conductivity of solid phases for neopentylglycol (NPG)-[x] wt.% D-camphor (DC), x = 0, 3, 30, 46, 70 and 96 alloys on temperature and composition have been investigated by using radial heat flow apparatus. From graphs of the solid phases thermal conductivity variations versus temperature, the thermal conductivities of the solid phases at their melting temperature and temperature coefficients for NPG-[x] wt.% DC, x = 0,3,30, 46, 70 and 96 alloys were found to be 0.29, 0.28, 0.27, 0.26, 0.25 and 0.24 W/Km and 0.002996, 0.002694, 0.005690, 0.010626, 0.003520 and 0.001404 K-1, respectively. The ratios of thermal conductivity of liquid phase to thermal conductivity of solid phase for NPG-[x] wt.% DC, x = 0, 3, 30, 46, 70 and 96 alloys at their melting temperature were found with a Bridgman type directional solidification apparatus to be 1.07, 0.93, 0.43, 0.50, 0.40 and 0.35, respectively. (C) 2011 Elsevier B.V. All rights reserved

NiTi SMA Parts Production with Different Porosity Ratios

NiTi SMA has widespread use in commercial and scientific fields with its recycling effect. Today, NiTi SMA alloys, which have different usage areas, are expected to have different properties. At the beginning of these properties, it is necessary to produce of the porosity structures (implant technology) and compact structure (high density material). For this reason, NiTi SMAs were produced with porous and compact structures in this study. Obtained theoretical densities were achieved from 57\% to 90\% in parts production

Grain Size and Grain Boundary Analysis of Aluminum Compacts with/without 10 wt.\% of Nickel Powder Processed by Equal Channel Angular Pressing

The aim of this study is to consolidate the Al-Ni powders using the equal channel angular pressing method in order to achieve improved structural and mechanical properties. Thus, both alloying ability at low temperature, as a result of consolidations of ultrafine grained alloy by equal channel angular pressing method, and the average grain size and grain boundary angle have been studied and the effect of Nickel has been investigated. Severe plastic deformation and consolidation process with 15 passes of equal channel angular pressing, having route C, have been carried out at 200 degrees C using pure aluminum and aluminum with 10 wt.\% of nickel. Electron backscatter diffraction was used to obtain scanning electron microscopy images and to determine the average grain size and average grain boundary angle. Density measurements of samples have been carried out using the Archimedes principle and the microhardness distributions have been obtained using the HV 0.5 method