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The effect of Ru addition on the martensitic transformation and mechanical properties of Zr50Pd50−xRux SMAs shape memory alloys has been studied. Strain–temperature experiments, differential scanning calorimeter, and scanning electron microscope analyses were performed to validate the theoretical predictions by DFT calculation regarding the influence of the C′ parameter on martensitic stability. Despite the absence of an observed shape memory effect under the tested conditions, the findings suggest that ZrPdRu alloys hold promise for high-temperature applications. [ABSTRACT FROM AUTHOR]

Alloying Pt with Rh significantly enhances the high temperature stress rupture strength and maintains both oxidation and corrosion resistance at elevated temperatures. Such unique property combination renders Pt-Rh alloys mainstay in space technology, glass and chemical industries. However, the exponential increase in the price of Rh in the past few years stirs an industrial concern. As a result, some industries are beginning to search for alternative alloys that can offer similar properties. This study conducted first-principles calculations to generate structural and elasticity data on binary Pt-Rh alloys using both supercell and virtual crystal approximation (VCA) approaches, to serve as a benchmark for new alternative Pt-based alloys.

MnPt-based alloys are promising new materials for magnetic recording and spintronic applications due to their interesting magnetic properties. The underlying thermodynamic properties are still unclear, despite numerous efforts to improve ferromagnetic stability through alloying. In this work, the phase stability of B2 and L10 PtMn1-xFex alloys is investigated using a combination of density functional theory (DFT) and Cluster Expansion (CE). CE model accuracy is evaluated against DFT data, where cross-validation scores were found to be reasonable. The CE generated 16 and 27 new structures on B2 and L10 PtMn1-xFex, respectively. The ground state line predicted 6 stable structures with negative formation energies for both B2 and L10 PtMn1-xFex alloys, suggesting thermodynamic stability. Furthermore, the magnetic strength of the ground state structures is evaluated using DFT.

Shape memory alloys (SMA's) are a special kind of metal alloys with unique structural properties, such as shape memory effect (SME) and pseudo-elasticity (SE) that were well-observed in TiNi alloy, which commercially trades as Nitinol. This polymorphic crystal behaviour arose from the reversible phase transition between an ordered high-temperature B2 and low-temperature martensite phase (L10/B19/B19′). Due to the high ductility of Ru, this work employed a supercell approach to track the effect of nickel addition on highly stable B2-Ti50Ru50 with the intent to stimulate SME. Thermodynamic, mechanical, electronic structure and lattice dynamic characteristics were estimated using first-principles calculations. The phonons spectra of B2 Ti50Ru50 consisted of only positive frequencies, but the addition of Ni above 18.75 at. % resulted in positive and negative frequencies, indicative of a possible martensitic transformation, which is a strong character for SME.

The backbone of the Monel alloys is built on the Ni-Cu system. As a result of their inherent properties such as high strength, toughness and excellent corrosion resistance, these alloys are widely used in marine, chemical and oil industries. A major setback of Ni-Cu alloys in application is the unsatisfactory wear performance. One way to get a grip around this issue is by understanding their fundamental properties. Thus, in order to lay a foundation for future materials development, this study employs first-principles approach to predict structural and mechanical properties of binary Ni-Cu austenitic alloys.

Due to the ferromagnetic nature of iron (Fe) and nickel (Ni) and most of their alloys, it is likely that their inherent magnetism could cause a defect called residual magnetism in welds. Although seldom explored, this property may contribute to the formation of brittle martensite and carbide phases by promoting carbon diffusion from the base material to the surface. This study focusses on solid-solution-strengthening (sss) of Ni electrode by alloying it with chromium (Cr) and copper (Cu), since the introduction of these metals is known to suppress magnetism while increasing strength.

NbRu has been considered as a potential high-temperature shape memory alloy due to its high martensitic transformation temperature, however, it has poor superelasticity and other shape memory properties, which limits its applications. In this paper, the effect of systematic substitution of Nb with Ti on the structural, thermodynamic, and elastic properties of supercell 2x2x2 B2 Ru50Nb50-xTix spanning the entire composition range (x = 0, 6.25, 12.50, 18.75, 25.00, 31.25, 37.50, 43.75, 50 at. %) is investigated using ab initio calculations. Elasticity results showed that the mechanical stability of the B2 phase improved with increasing Ti content, which could be associated with a decrease in transformation temperature. However, a suitable composition range within which Cʹ~0, resembling that of well-known TiNi, is identified. This predicts Ti addition to be effective in improving shape memory properties of B2 NbRu alloy.

This study presents the analysis of the microstructure and Vickers micro-hardness of β-Ti type Ti-15.05Mo alloy obtained by different cooling rates. The alloy was fabricated using an arc-melting furnace, solution treated in a muffle furnace and cooled using different cooling medium such as ice water, furnace cool and air cooling. The X-ray analysis of the as-cast showed β phases peaks only and water quenched samples showed peaks belonging to α″ and β phases. The (β, α) dual phases were detected in the furnace and air-cooled samples, respectively. The Optical Microscope (OM) micrographs of the as-cast Ti-15.05Mo sample showed large equiaxed β grains and sub-structures belonging to orthorhombic martensitic α″ phase. The water quenched sample showed β equiaxed grains, however their grains were much smaller You should leave 8 mm of space above the abstract and 10 mm after the abstract. The heading Abstract should be typed in bold 9-point Arial. The body of the abstract should be typed in normal 9-point Times in a single paragraph, immediately following the heading. The text should be set to 1 line spacing. The abstract should be centred across the page, indented 17 mm from the left and right page margins and justified. It should not normally exceed 200 words.

Metal dusting is described as a severe form of corrosion attack in which iron, steels, nickel- and cobalt-based alloys disintegrate into metal or metal carbide particles in a coke deposit when exposed to strongly carburising gases (carbon activity ac>1) at elevated temperatures (300-800°C). Despite intense research efforts, which led to much progress in mitigating metal dusting, particularly in the oil and gas industry, the complete prevention still remains an issue. Current study focuses on measuring corrosion resistance of heat-treated austenitic Ni, Ni-Cr-based complex alloy compositions containing iron and copper as additional alloying elements.

Water quenching of unmilled Ti compact has yielded martensitic-type laths and fishbone-type twinned microstructures, with α', α'' and FCC phases induced. Upon quenching 30 h milled and (0+30) h mixed powders at 1200 °C, α', FCC, tetragonal and BCC phases were detected using XRD. [ABSTRACT FROM AUTHOR]

The alloying effect of three elements, namely Al, Cr and Zn, on the Pt site of L12 Cu3Pt phase was investigated using DFT (density functional theory) based first-principle calculations in attempt to stabilize it in the form of L12 Cu3Pt1-xYx ternary alloy. On the basis of phase stability and elastic properties, the substitution behaviour of all three alloying elements were compared with properties of thermodynamically sluggish Cu3Pt phase. The calculated heats of formation reveal that the thermodynamic phase stability is gradually enhanced with increasing content of aluminium alloying and diminished with increasing content of zinc and chromium. In this current work, the stress-strain approach was used according to Hooke’s law to calculate elastic properties such as elastic constants, Young’s modulus E, shear modulus G, bulk modulus B and Poisson’s ratio v, as they play an important role to investigate the resulting mechanical properties. The calculated results show that alloying with all three elements maintains the mechanical stability criteria of cubic crystals. Considered L12 Cu3Pt1-xYx ternary alloys exhibit the most ductile character with Al addition, followed by Cr, whereas introduction of Zn yielded lowest ductility at higher compositions.

More recently, the L10 MnPt alloy has received massive attention in data storage applications such as spintronics due to its high ferromagnetic stability and very high Néel temperature. It was found that L10 MnPt alloy showed ferromagnetic behaviour at room temperature. In this study, the effect of introducing antiferromagnetic (Cr) and ferromagnetic (Fe) elements on MnPt alloy is being investigated using density functional theory (DFT). The thermodynamic stability was determined from the heats of formation to check the formability of Pt50Mn50-xMx (M= Cr, Fe; x=6.25, 12.5, 18.75, 25) alloys. These Pt50Mn50-xMx alloys were found to be thermodynamically stable although with lower heats of formation. Overall magnetic moments decrease slightly with an increase in Cr and Fe compositions, only at 6.25 at. % Cr the ferromagnetic state is improved when the c/a ratio is 1.10. The current work revealed that the DFT-based first-principle approach can be used to design new possible compositions for the development of PGM-bearing magnetic materials.

Cesium-chloride (CsCl) based intermetallic alloys that are formed between Ti and Group VIIIB and IB metals (Fe, Ni, Ru, Rh, Pd, Os Ir, Pt and Au) are currently explored for various potential applications as hydrogen storage, shape memory and biomedical materials. These compounds display excellent structural properties such as high strength due to their stable B2 phase at elevated temperatures. However, when some are subjected to unfavourable conditions such as lower temperature they become unstable and undergo a phase transition to low symmetry phases. In this work, we conducted a detailed comparative study using both VASP and CASTEP codes to carry out the first-principles calculations. Phase stability and martensitic phase transition were evaluated from the enthalpies of formation, the density of states as well as the phonon dispersion curves. There was no frequency gap observed on phonons density of states (PHDOS) spectra of the investigated compounds containing noble transition metals due to higher d-orbital electron filling.

Austempered ductile iron (ADI) is a new engineering material type which continue receiving increased attention in research and industry. Extensive research conducted so far has demonstrated that ADI has excellent property combination such as high strength-weight ratio, ductility and toughness, good fatigue strength, damping properties and wear resistance. As a result of to their exceptional mechanical property mix, fabrication simplicity, low cost and lowest weight per unit strength ratio compared to common steels, this family of ferrous cast alloys have begun replacing cast and forged steels in some engineering applications. However, a major limiting factor to widespread use of ADI in manufacturing industry remains its weldability, more especially during fabrication process. Current work presents a review of various filler materials (electrodes) used to weld ductile cast iron using two common industrial welding processes, namely, shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). The successes as well as short-comings of these electrodes on weldability of ductile iron have been recorded and a clear need for an improved filler material is identified.

This study presents the phase analysis, microstructural characteristics, and mechanical property evaluation of the as-cast and quenched Ti-15Mo-xFe alloys with high iron content ranging from 4 to 12 weight percent. All the four alloys were produced in a vacuum-arc melting furnace. Heat treatment in the form of solution treatment was performed in a muffle furnace at a temperature of 1100 °C, with 1-h holding time and the samples were rapidly quenched in ice-brine. X-ray diffractometer (XRD) was used to analyses the phases present in each alloy whereas the optical microscope (OM) was employed to track the microstructural evolution and percentage porosity. The mechanical properties of the alloys were evaluated using a tensile test and compression test method while the micro-Vickers hardness measurements were conducted to evaluate hardness of the alloys. The XRD patterns of as-cast showed peaks belonging to the β and α″ phases and intermetallic B2 TiFe phases. The as quenched XRD peaks illustrated β phase only and Fe·Ti·O 2 phases. The as-cast OM micrographs revealed equiaxed β grains, substructures, dendritic structure, and pores forming around the grain boundaries. The quenched OM showed only β equiaxed grains with pores throughout the grain boundaries. The tensile properties such as ultimate tensile strength (UTS) and elastic modulus (E) of as-cast TMF0 were 264 MPa and 79 GPa respectively and these properties changed upon quenching to 411 MPa and 66 GPa respectively. The elastic modulus of TMF1 in as-cast condition was 74 GPa. The UTS and E of TMF1, TMF2, and TMF3 in as-cast and quenched conditions were not recorded due to the fragility of the samples that failed prior to yielding any useful data. The compressive strength in as-cast and in quenched condition decreased with an increase in Fe content. The micro-Vickers hardness in as-cast and quenched conditions showed a similar trend with hardness increasing slightly upon quenching for TMF0, TMF1, and TMF3 alloys but slightly decreased in the case of TMF2. The fracture surfaces of all the as-cast and quenched alloys were comprised of ductile and brittle fracture., (© 2024. The Author(s).)

MnPt's exceptional stability and extremely high Néel temperature have generated a lot of interest in data storage applications. Previously, it was reported experimentally that the MnPt alloy shows ferromagnetic (FM) behavior at room temperature. In this study, the effects of partial substitution of Pt with Pd, Au, and Ag on magnetic properties is investigated using density functional theory. The stability of Mn 50 Pt 50-x M x (M = Pd, Au, Ag, x = 6.25, 12.5, 18.75) alloys was assessed by determining their thermodynamic, magnetic, and mechanical properties. The calculated lattice constants of Mn 50 Pt 50 agree well with available theoretical results. The Mn 50 Pt 50-x M x alloys' formability was assessed by measuring the thermodynamic stability using the heat of formation. It was found that B2 Mn 50 Pt 50-x Pd x alloys (0 ≤ x ≤ 18.75) are thermodynamically stable due to the negative heat of formation close to that of a pristine MnPt alloy. Based on the elasticity results, the B2 Mn 50 Pt 50-x Pd x is most likely to undergo martensitic transformation for the entire considered composition range. From the calculated values of the Poisson's ratio, it is shown that an increase in Pd, Ag, and Au effectively improves the ductility of the B2 Mn 50 Pt 50-x M x compounds. It was revealed that ferromagnetism is maintained with Pd addition but significantly reduced in the case of Au and Ag. Thus, this work showed that density functional theory can be exploited to propose new possible compositions for future magnets in spintronic applications.

Factor XIII, a transglutaminase that plays a crucial role in clot formation, consists of subunits A and B. Single nucleotide polymorphisms in Factor XIII-A have been linked to thrombotic risk. In Type 2 Diabetes mellitus (T2DM), a hypercoagulable state is thought to contribute to the high mortality rate associated with thrombotic diseases. Due to the lack of prevalence data of FXIII-A single nucleotide polymorphisms (SNPs) in T2DM in a South African cohort, this study assessed the prevalence FXIII-A Val34Leu (rs5985) and Tyr204Phe (rs3024477) SNP's and the effect on clot kinetics in T2DM., Materials and Methods: A cohort of T2DM patients (n = 100) and race, age and gender matched healthy controls (n = 101) were recruited following ethical approval. Thromboelastography® (TEG®) was used to assess the viscoelastic properties in platelet poor plasma (PPP) in controls (n = 91) and T2DM patients (n = 91) younger than 50 years old. Genomic DNA was isolated from whole blood using the Quick-DNA™ Miniprep Plus Kit and PCR-RFLP was used to genotype each sample for FXIII-A rs5985 and rs3024477 SNPs., Results: TEG® analyses indicated a longer R-time (p < 0.0001) and higher TMRTG (p < 0.0001) in PPP of T2DM patients. Control and T2DM genotype distribution conformed to Hardy-Weinberg equilibrium (p > 0.05). There was a higher prevalence of the wildtype genotype of FXIII-A Tyr204Phe (rs3024477) SNP in T2DM (OR = 0.23, 95% CI = 0.12-0.42, p < 0.0001). The 204Phe variant was more frequent in the Caucasians (OR = 0.39, 95% CI = 0.05-0.33, p < 0.0001). The presence of the 204Phe variant in T2DM affected TMRTG (p = 0.0207). The variant affected R time (p = 0.0432) and TMRTG (p = 0.0209 and p = 0.0207) in controls and T2DM, respectively., Conclusion: An inverse association with T2DM and FXIII-A Tyr204Phe was found. A hypo coagulable PPP clot profile was observed in T2DM. A shorter reaction time was observed and but faster rate at which the clot reached maximum strength in both controls and T2DM in the presence of the 204Phe variant., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Fusarium circinatum is an important pathogen of pine trees. However, little is known regarding the molecular processes underlying its pathogenesis. We explored the potential role of the phytotoxin fusaric acid (FA) in the pathogenicity of the fungus. FA is produced by products of the FUB biosynthesis gene cluster, containing FUB1-12. Of these, FUB1 encodes the core polyketide synthase, which we disrupted. We used the resulting mutant strain to investigate whether FUB1 and FA production play a role in the virulence of F. circinatum on pine. Our results showed that FA production was abolished both in vitro and in planta. However, bikaverin production was increased in the knockout mutant. FUB1 disruption also corresponded with downregulation of a F. circinatum homologue of LaeA, a master transcriptional regulator of secondary metabolism. Lesion lengths produced by the FUB1 knockout mutant on inoculated Pinus patula seedlings were significantly smaller than those produced by the wild type strain. Collectively, these results show that FUB1 plays a role in FA production in F. circinatum, and that this gene contributes to the aggressiveness of F. circinatum on P. patula. This study will contribute to the limited knowledge we have about the molecular basis of pathogenicity in this fungus., Competing Interests: Declarations of competing interest None., (Copyright © 2021 British Mycological Society. Published by Elsevier Ltd. All rights reserved.)

In this study, we investigated to possible role of Ras2 in Fusarium circinatum- a fungus that causes pine pitch canker disease on many different pine species and has a wide geographic distribution. This protein is encoded by the RAS2 gene and has been shown to control growth and pathogenicity in a number of fungi in a mitogen-activated protein kinase- and/or cyclic adenosyl monophosphate pathway-dependent manner. The aim was therefore to characterize the phenotypes of RAS2 gene knockout and complementation mutants of F. circinatum. These mutants were generated by transforming protoplasts of the fungus with suitable split-marker constructs. The mutant strains, together with the wild type strain, were used in growth studies as well as pathogenicity assays on Pinus patula seedlings. Results showed that the knockout mutant strain produced significantly smaller lesions compared to the complementation mutant and wild type strains. Growth studies also showed significantly smaller colonies and delayed conidial germination in the knockout mutant strain compared to the complement mutant and wild type strains. Interestingly, the knockout mutant strain produced more macroconidia than the wild type strain. Collectively, these results showed that Ras2 plays an important role in both growth and pathogenicity of F. circinatum. Future studies will seek to determine the pathway(s) through which Ras2 controls these traits in F. circinatum., (Copyright © 2021 Elsevier Inc. All rights reserved.)