A comparison of the microstructures, thermal and mechanical properties of pressed and sintered TieCu, TieNi and TieCueNi alloys intended for dental applications

The effect of Ni and Cu on the a/b phase transformation temperature, possible retention of the b-phase, and mechanical properties of Ti, Tie13Cu, Tie4.5Ni and Tie13Cue4.5Ni (compositions in wt. %) alloys were investigated. The alloys were developed using the conventional uniaxial cold press and sintering technique. The thermal properties of the sintered alloys were traced by the differential scanning calorimetry (DSC) analysis. The x-ray diffraction (XRD) and electron backscatter diffraction (EBSD) analysis determined phase composition, crystal structures and grain orientations. It has emerged that the Ti e13Cu and Tie13Cue4.5Ni retained the b-Ti phase. The mechanical properties were evaluated under tension with Tie13Cu and Tie4.5Ni possessing high ultimate tensile strength (UTS) and percentage elongation (%El) than the Tie13Cu-4.5Ni alloy. Although all the alloys have revealed the presence of porosity, its effect on mechanical properties was more on the Tie13Cue4.5Ni alloy. While the mechanical properties of Tie13Cu-4.5Ni alloy were inferior due to extensive porosity, those of Ti, Tie13Cu and Ti e4.5Ni allow them to be classified as Type 3 and Type 4 dental alloys, respectively, proving that the conventional powder metallurgy process has potential to be used as a processing technique for TieCubased dental alloys

Investigating the mechanical properties of A356 (Sr doped) using mechanical stirring

The Aluminium alloy A356 alloy is primarilyusually used for automobile and aerospace components owing to its high strength to weight ratio, and its relatively good corrosion resistance. The effectiveness of the economical stir casting method was investigated by adding the strontium (Sr) metal uniformly to aid in the modification of the alloy’s eutectic morphology for improved mechanical properties. The addition of ̴0.63 wt% Sr addition resulted into grain refinement which improved the mechanical properties whereby the ultimate tensile strength (UTS) increased from 200 MPa to 250 MPa, Yield strength increased from 85 MPa to 100 MPa and the microhardness was increased from 74.94 Hv to 87.10 Hv

Vacuum melting of compressed powders and hot rolling of the as-cast Ti-48Al-2Nb-0.7Cr-0.3Si intermetallic alloy : mechanical properties and microstructural analysis

The amalgamated effect of hot-rolling, rapid cooling and heat treatment on the grain refinement and the resultant mechanical properties of an intermetallic sheet of nominal composition Ti-48Al-2Nb-0.7Cr-0.3Si was investigated. The sheet of 4 mm thickness was fabricated by hot-pack rolling from the vacuum arc remelted (VAR) ingot using a conventional two-high rolling mill. After the final rolling pass, the canned specimen was rapidly cooled in the air to room temperature followed by heat treatment in the α + γ region. The scanning electron microscopy (SEM) micrographs of the as-rolled sheet revealed slightly elongated grains of a typical “duplex (DP)” microstructure with a mean grain size of about 3 μm which grew to about 4 μm and became more equiaxed and homogeneous after heat treatment. Moreover, the EBSD micro-texture indicated a weak cube texture in the rolled + heat-treated sheet. Furthermore, the results from the profilometry-based indentation plastometry of the rolled + heat treated specimen illustrated the balanced and improved mechanical properties compared to the as-cast and as-rolled samples, and also those of similar alloy systems found in the literature.The Council of Scientific and Industrial Research, the University of Pretoria and Mintek.https://www.elsevier.com/locate/manpro2024-07-11hj2023Materials Science and Metallurgical Engineerin

Powder characteristics blending and microstructural analysis of a hot-pack rolled vacuum arc-melted γ-tial-based sheet

In the quest for cost-effective fabrication processes capable of producing sound γ-TiAl products, the microstructure and mechanical properties of a modified second-generation hot-rolled γ-TiAl-based alloy with nominal composition Ti-48Al-2Nb-0.7Cr-0.3Si were investigated in this work. The alloy was fabricated using a processing route that involved uniaxial cold-pressing of powders and vacuum arc re-melting. Prior to the cold pressing, the elemental powder characteristics, such as particle sizes and morphologies, were blended to minimise porosity in the compact that might be inherited by the final ingot. A hot-pack rolling process was carried out directly from the melted button-ingot using a conventional two-high rolling mill to produce a 4 mm-thick sheet. The relative density results of both as-compacted and as-melted alloy parts showed a significant reduction of porosity in the alloy. In addition, both the optical and the scanning electron microscopy micrographs of the rolled sheet revealed a typical 'duplex' microstructure with a mean grain size of about 9 urn. Moreover, the results from a room-temperature indentation plastometry test of the hot-rolled sheet indicated good mechanical properties with recorded yield strength of about 600 MPa, an ultimate tensile strength of about 850 MPa, and a true plastic strain of about 3%.In 'n soektog na koste-effektiewe vervaardigingsprosesse wat in staat is om goeie γ-TiAl-produkte te produseer, is die mikrostruktuur en meganiese eienskappe van 'n gemodifiseerde tweedegenerasie warmgewalste γ-TiAl-gebaseerde legering met nominale samestelling Ti-48Al-2Nb-0.7Cr-0.3Si ondersoek. Die legering is vervaardig deur gebruik te maak van 'n verwerkingsroete wat eenassige koue pers van poeiers en vakuumbooghersmelting behels. Voor die koue pers is die elementêre poeierkenmerke, soos deeltjiegroottes en morfologieë, vermeng om porositeit in die kompak te minimaliseer wat deur die finale steen geërf kan word. 'n Warmpak-walsproses is direk vanaf die gesmelte knoppiesblok uitgevoer met behulp van 'n konvensionele twee-hoë walswerk om 'n 4 mm-dik plaat te vervaardig. Die relatiewe digtheidsresultate van beide as-saamgepakte en as-gesmelte legeringsdele het 'n beduidende vermindering van porositeit in die legering getoon. Daarbenewens het beide die optiese en die skandeer-elektronmikroskopie mikrograwe van die gerolde vel 'n tipiese "dupleks" mikrostruktuur met 'n gemiddelde korrelgrootte van ongeveer 9 urn geopenbaar. Boonop het die resultate van 'n kamertemperatuur inkepingsplastometrietoets van die warmgewalste plaat goeie meganiese eienskappe met aangetekende vloeisterkte van ongeveer 600 MPa, 'n uiteindelike treksterkte van ongeveer 850 MPa en 'n ware plastiese vervorming van ongeveer 3% aangedui.Presented at the 23rd Annual International Conference of the Rapid Product Development Association of South Africa (RAPDASA) Institute for Industrial Engineering, held from 9 to 11 November 2022 in Somerset West, South Africa.The Council of Scientific and Industrial Research.http://sajie.journals.ac.zaam2023Materials Science and Metallurgical Engineerin