A review on crucibles for induction melting of titanium alloys

This review highlights the state of art progress in crucible designs which have been identified as showing potential for induction melting three groups of titanium alloys based on the systems; Ti–Al, Ti–Ni, as well as multicomponent Ti-based hydrogen storage alloys. Several important parameters for crucible design, including; crucible-melt interactions, thermodynamic stability, and, thermal shock resistance of different crucibles will be discussed. Based on the findings of the review, the selection criteria for identifying crucibles for melting titanium alloys were outlined and several specific promising solutions were suggested

Electrochemical deposition of silver and copper from a deep eutectic solvent studied using time-resolved neutron reflectivity

Here, we describe new developments in the study of electrodeposition processes with time-resolved dynamic neutron reflectivity (NR) methods to achieve insights into the differences between growth of metal films using a range of electrochemical control functions. We show that the temporal resolution has increased from 1 to 2 h per data set (in our previous studies) to approximately 8 min. We have studied the electrochemical deposition of copper and silver as thin-film metals onto a gold electrode substrate from a deep eutectic solvent using potentiodynamic (PD), potentiostatic (PS) and galvanostatic (GS) electrochemical control functions. In particular, we have utilised novel developments in neutron reflectivity methods to acquire real-time data for the growing metal films. Event mode capture of neutron scattering events, as a function of momentum transfer vector, Q, during electrochemical growth has enabled time-resolved measurement of the neutron reflectivity, R(Q), profiles of the growing metal films. Subsequent fitting and iterative optimisation of the R(Q,t) data reveals the thickness, roughness and relative density (spatially resolved solvent content) of the metal film during growth. These data show that the different electrochemical growth methodologies exhibit different trends in thickness, roughness and solvation. Silver films show an increasing roughness trend with time but these trends are largely independent of growth method. In contrast, the roughness of copper films, grown under similar conditions, shows a strong dependency on growth method with PS methods producing smoothest films. These conclusions are confirmed by ex-situ AFM measurements. The fitted NR data show that the Cu and Ag films contain between 5 and 10% volume fraction solvent. Furthermore, we have explored different NR data fitting methodologies in order to process the large numbers of data sets produced. Gratifyingly, the different methodologies and starting conditions yield a very consistent picture of metal film growth

Metal hydride hydrogen storage and compression systems for energy storage technologies

Along with a brief overview of literature data on energy storage technologies utilising hydrogen and metal hydrides, this article presents results of the related R&D activities carried out by the authors. The focus is put on proper selection of metal hydride materials on the basis of AB5- and AB2-type intermetallic compounds for hydrogen storage and compression applications, based on the analysis of PCT properties of the materials in systems with H2 gas. The article also presents features of integrated energy storage systems utilising metal hydride hydrogen storage and compression, as well as their metal hydride based components developed at IPCP and HySA Systems

Development and Performance of High Chromium White Cast Irons (HCWCIs) for Wear–Corrosive Environments: A Critical Review

There is a huge demand for high-performance materials in extreme environments involving wear and corrosion. High chromium white cast irons (HCWCIs) display better performance than many materials since they are of sufficient hardness for wear protection and can be tailored in chemical compositions to improve corrosion resistance; however, their performance is often still inadequate. This article reviews the chemical composition and microstructure design aspects employed to tailor and develop HCWCIs with combined corrosion and wear resistance. The performance of these alloys under wear and corrosion is reviewed to highlight the influence of these parameters in the industry. Existing challenges and future opportunities, mainly focusing on metallurgical alloy development aspects like chemical composition, casting, and heat treatment design, are highlighted. This is followed by suggestions for potential developments in HCWCIs to improve the performance of materials in these aggressive environments. Many variables are involved in the design to obtain suitable microstructures and matrix composition for wear–corrosion resistance. Computational modeling is a promising approach for optimizing multi-design variables; however, reliable field performance data of HCWCIs in wear–corrosion environments are still inadequate. Quantitative evaluation of the wear–corrosion performance of HCWCIs requires the development of laboratory and field tests using standard conditions like abrasive type and sizes, severity of loading, slurry velocity, pH, and temperature to develop wear–corrosion maps to guide alloy development

Decolonizing Healthcare: a Black Feminist Analysis of Sisters Informing Sisters on Topics of AIDS (SISTA)

This mixed methods project combines the conceptual insights offered by institutional ethnography, the deductive and inductive attributes of content analysis, semi structured interviews, and quantitative data analysis to study Sisters Informing Sisters on Topics of AIDS (SISTA), a social skills training program designed for sexually active, heterosexual African American women. This progressive program serves as a site to examine the complex relationship the U.S. state has had, and continues to have, with marginalized populations, particularly African Americans. The program reveals how the state, through the public health service, partners with scholars, researchers, and community-based organizations to produce, reproduce and perpetuate problematic discourses regarding the sexual lives of Black folks. As a former participant in this training, I juxtapose the theory of gender and power, upon which the program rests, to standpoint feminist theories like Black Feminist Thought to show the ways class and colorblind racism work together in well-intentioned programs to ensure the survival of controlling images. I argue that though SISTA offered a variety of benefits to the community, it is still a valuable source of data into the ways harmful stereotypes about the sexual lives of Black folks concerning HIV/AIDS exposure persist even in the face of opposing discourse like Black Feminist Thought

Solidification sequence and phase equilibria in Ti-47Al-22Nb and Ti-47Al-20Nb ternary alloys

The phase transformation sequences and phase equilibria in Ti-47Al-20Nb and Ti-47Al-22Nb (at.%) alloys were investigated through experiments and computational (CALculation of PHAse Diagrams) techniques. Experiments to study nonequilibria phase transformations involved quenching the alloys from high temperature followed by composition and microstructure characterization. The computed results show that with increase in temperature, the α  +  β  +  γ tie-triangle phase region shifts towards low Nb content. On the contrary, experimental results show that with increase in temperature the tie-triangle of α  +  β  +  γ moves towards high Nb content. These changes are attributed to the expansion of the α phase region and corresponding changes of the primary α , β and γ phase regions with increase in temperature. In the experimentally studied alloys, a part of the α phase transformed to γ phase by massive transformation and most of the β phase transformed to γ phase in high Nb content alloys

Modification of Precipitate Coarsening Kinetics by Intragranular Nanoparticles—A Phase Field Study

Precipitate coarsening is a major mechanism responsible for the degradation in mechanical properties of many precipitation-hardened alloys at high temperatures. With recent developments in processing of nanocomposite materials, a substantial volume fraction of inert second phase ceramic nanoparticles can be introduced into the grain interiors of polycrystalline materials. These intragranular nanoparticles can have synergistic effects of impeding dislocation motion and interacting with coarsening precipitates to modify the coarsening rate. In this work, the precipitate coarsening behavior of an alloy in the presence of intragranular inert nanoparticles was studied using the phase field method. Two key measurements of coarsening kinetics, precipitate size distribution and coarsening rate, were found to be affected by the volume fraction and the size of nanoparticles. Two novel mechanisms related to geometric constraints imposed by inter-nanoparticle distance and the blockage of solute diffusion path by nanoparticle–matrix interfaces were proposed to explain the observed changes in precipitate coarsening kinetics. The simulation results in general suggest that the use of small nanoparticles with large number density is effective in slowing down the coarsening kinetics