Mechanistic Undrestanding Of Amorphization In Iron-Based Soft Magnetic Materials

Iron-based magnetic alloys possess very good magnetic and mechanical properties. Among these alloys Fe-Si-B-based alloys show outstanding saturation magnetization and coercivity which makes them great candidates for many industrial applications. Addition of certain elements to the Fe-Si-B base is proven to improve the homogeneity and fineness of microstructure as well as enhance the magnetic behavior of these alloys. In this research work, we have studied the effect of adding copper and niobium to the Fe-Si-B base alloy. Previous studies have shown that magnetic alloys show better magnetic properties when their microstructure consists of nanocrystals embedded in an amorphous matrix. In order to reach amorphization, magnetic alloys are traditionally melted and then cooled down very fast to prevent crystallization and grain growth in their microstructure. However, there are several disadvantages associated with this method of fabrication, such as the limitation in thickness of the products. To solve this issue, we proposed a new method of fabrication for magnetic alloys where amorphization occurs through mechanical alloying, and the amorphous powder alloy that is produced by this process is then consolidated using a technique called spark plasma sintering finding appropriate mechanical alloying processing parameters to get an amorphous structure. Many different processing parameters were investigated, and the mechanical properties, microstructure, and magnetic properties of all samples were examined. The effect of spark plasma sintering processing parameters on samples sintered from the amorphous powders was then studied. Finally, the amount of energy introduced to the powder from the milling balls during the mechanical alloying process was calculated. We were able to find a trend between the energy introduced to the powder during the milling process and the amorphous structure of the milled powders. From our data, we draw an energy map that shows the window of total energy in which the powder, regardless of the mechanical alloying processing parameters under which it was milled, will show an amorphous structure. This area has not been explored for these magnetic alloys before, and this data can be used by researchers who are trying to obtain amorphization via the mechanical alloying process

Spark Plasma Sintering of Soft magnetic Materials

Over the past 3 decades, iron-based soft magnetic alloys such as Finemet (Fe73.5Si13.5B9Nb3Cu1 (at%)) have attracted great interest due to their exceptional magnetic properties like high magnetization, low coercivity, and high curie temperature. However, the production of amorphous precursor requires very high cooling rates, and thus only wires, powders, and thin ribbons are achievable, yet these are not suitable in industrial applications where large volume of bulk magnetic components is required. Mechanical alloying (MA) has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering (SPS) is a unique technique for processing dense and near net shape bulk amorphous-nanocrystalline alloys with homogenous microstructure. The iron-based soft magnetic alloys have been fabricated by spark plasma sintering (SPS) process coupled with high energy ball milling. All the alloys have been processed from a mechanically alloyed blend of elemental powders, and their microstructures, microhardness, and phase formation are discussed. In addition, influence of ball milling parameters on microstructure and phase formation of these alloys have been investigated. This study will open new avenues for the development of soft magnetic materials, with complex shapes and excellent soft magnetic properties.https://engagedscholarship.csuohio.edu/u_poster_2018/1072/thumbnail.jp

Measuring urban social sustainability: Scale development and validation

Despite the significant role of social sustainability in the sustainable development agenda, there is a lack of research to clearly define and fully operationalise the concept of urban social sustainability. The aim of this study is to contribute to the existing literature by developing a comprehensive measurement scale to assess urban social sustainability (USS) at the neighbourhood level. We argue that urban social sustainability is a multidimensional concept that incorporates six main dimensions of social interaction, sense of place, social participation, safety, social equity, and neighbourhood satisfaction. Failure to consider each of these dimensions may lead to an incomplete picture of social sustainability. Validity, reliability and dimensionality of the USS scale are examined using factor analysis. We also illustrate the application of the USS scale by investigating the influence of quality of design, as one of the least studied factors of urban form, on different dimensions of social sustainability. The paper uses data collected from the household questionnaire survey in a sample of 251 respondents from five case study neighbourhoods of Dunedin city, New Zealand. This study provides new evidence on the significance of improving neighbourhood quality of design and its positive and significant relationship with different dimensions of social sustainability and the overall social sustainability

The use of morphological description in neighbourhood planning: form-based assessment of physical character and design rules

Despite ongoing efforts to encourage the use of urban morphology tools into current practice, uptake remains limited. Shortcomings are largely attributed to time and resource intensive methods of historical settlement transformation study. However, developments in quantitative morphological approaches offer new possibilities for efficiency and easier adoption of research tools in practice. This paper proposes the use of typo-morphology methods to inform the adoption of form-based design guidance in neighbourhood master plans. The aim of the study is to develop a comprehensive yet flexible method for form-based character assessment (FBCA) of residential streets. The resulting FBCA classification identifies streets where compliance with form-based design rules could be tightened. The FBCA method is empirically tested in the context of the local neighbourhood plan for Radlett, Hertfordshire in the United Kingdom, offering reflections from practice on the usefulness and limitations of the method

Frustrated Double Ionization of Argon Atoms in Strong Laser Fields

We demonstrate kinematically complete measurements on frustrated double ionization of argon atoms in strong laser fields with a reaction microscope. We found that the electron trapping probability after strong field double ionization is much higher than that after strong field single ionization, especially in case of high laser intensity. The retrieved electron momentum distributions of frustrated double ionization show a clear transition from the nonsequential to the sequential regime, similar to those of strong field double ionization. The dependence of electron momentum width on the laser intensity further indicates that the second released electron has a dominant contribution to frustrated double ionization in the sequential regime

Spark Plasma Sintering of Low Modulus Titanium-niobium-tantalum-zirconium (TNTZ) Alloy for Biomedical Applications

In metallurgy, titanium has been a staple for biomedical purposes. Its slow toxicity and alloying versatility make it an attractive choice for medical applications. However, studies have shown the difference in elastic modulus between titanium alloys (116 GPa) and human bone (10–40 GPa), which contributes to long term issues with loose hardware fixation. Additionally, long term studies have shown elements such as vanadium and aluminum, which are commonly used in Ti-6Al-4V biomedical alloys, have been linked to neurodegenerative diseases like Alzheimer and Parkinson. Alternative metals known to be less toxic are being explored as replacements for alloying elements in titanium alloys. This study will focus on advanced processing and characterization of β-phase titanium alloys for biomedical applications. The microstructure, mechanical, and electrochemical properties of these alloys have been analyzed and compared with C.P. titanium. Bond order B¯O role= presentation \u3e and energy level M¯D role= presentation \u3e approach has been used to design these alloys in order to achieve low elastic modulus. The main objective is to study the effect of different alloying elements on microstructure, phase transformation and mechanical properties of these newly developed low modulus β-phase titanium alloys and establish new avenues for the future development of biocompatible titanium alloys with optimum microstructure and properties