Neutron scattering studies of hard metals

Since their discovery about 100 years ago, tools made of hard metals have been the enablers of development in various areas: from drilling subway lines for more sustainable cities to the machining of complex next-generation airplane engine parts for reduced CO2 emissions. An increase in properties of hard metals thus leads to efficient operations with shorter lead-time, less environmental footprint, and reduced cost. To tailor the as-sintered hard metal structure with desired properties and develop reliable modelling tools, it is critical to have statistically representative experimental data acquired in conditions mimicking the real processes for hard metals. However, to date, nano- and microstructural investigations of hard metals and related systems have been mainly focused on the lab-scale techniques, limiting the bulk-scale in-situ investigations.  This thesis focuses on neutron scattering techniques and demonstrates how the utilization of small angle neutron scattering (SANS) techniques and neutron diffraction (ND) in a complementary manner with lab-scale techniques and computational tools can enhance the mechanistic understanding during processing of hard metals and related systems. Some of the presented information within the thesis is unique to neutron scattering experiments. SANS experiments are used for the quantification of nano- and microstructural features including Co-rich binder pocket size, WC grain size, and size and volume fraction of (V,W)Cx interfacial layers. The quantitative data enables us to draw conclusions regarding the mechanism of grain coarsening inhibition in V-doped hard metals at different V additions. The findings indicate that the grain coarsening inhibition in V-doped hard metals originates from reduced WC/Co interface mobility and total driving force for coarsening. The complex nature of structural evolution at sintering temperatures is further investigated by in-situ SANS up to 1500 oC. Our results show that the size and volume fraction of interfacial layers strongly depend on the presence of bulk (V,W)Cx precipitates and V activity in the binder phase. In-situ ND experiments during aging of (Ti,Zr)C-based systems provide time-resolved insights into the kinetics and structural evolution during phase separation at 1600 oC for 10 h. The results reveal that the decomposition of (Ti,Zr)C into TiC- and ZrC-rich phases can be significantly retarded by minor HfC or NbC additions. During decomposition, in line with the nucleation and growth process, no change is observed in the lattice parameter of ZrC-rich phase. In contrast, the lattice parameter of TiC-rich phase reduces with decomposition, resulting from TiC enrichment, i.e. it reaches equilibrium composition in the course of time. Furthermore, a novel multi-principal element carbide system (Ti,Zr,Hf,W)C with exceptional hardness is designed. Although the system has a miscibility gap, only minor decomposition is observed after 100 h aging at 1350 oC, where the formation of (Ti,W)C- and (Zr,Hf)C-rich decomposition products and WC precipitates occur. Such hindered decomposition enables the carbide system to preserve its high hardness. In summary, by using neutron scattering techniques, this thesis contributes to a better understanding of nano- and microstructural evolution in hard metals and related systems during their processing at elevated temperatures. The thesis and appended papers also guide readers regarding the planning, e.g. sample preparation and sample environment selection, and data analysis of neutron scattering experiments. The thesis can thus serve as a starting point for the more widespread utilization of neutron scattering techniques by the hard metal industry.Sedan upptäckten av hårdmetall för cirka 100 år sedan har verktyg gjorda av hårdmetall varit avgörande för tillämpningar inom olika områden såsom borrning av tunnelbanelinjer för mer hållbara städer och bearbetning av nästa generations flygplansmotorer för minskade CO2-utsläpp. Förbättrade egenskaper hos hårdmetallen leder således till ökad effektivitet i olika verktygsoperationer med kortare ledtid, mindre miljöpåverkan och minskade kostnader för till exempel tillverkning. För att skräddarsy den sintrade hårdmetallstrukturen och skapa önskade egenskaper är det viktigt att ha statistiskt representativ experimentell data som uppmätts under förhållanden som efterliknar de verkliga processerna inom industrin. Hittills har dock nano- och mikrostrukturundersökningar av hårdmetaller och relaterade system huvudsakligen varit begränsade till laboratorietekniker, vilket begränsat in-situ-undersökningar av materialens bulk.  Den här avhandlingen använder neutronspridningstekniker på olika relevanta hårdmetallsystem och visar på hur lågvinkelspridning (SANS) och neutrondiffraktion (ND) kan komplettera konventionella laboratorietekniker och beräkningsverktyg för att förbättra förståelsen av meknismer som styr materialets utveckling under olika processer. En del av datat som presenteras i avhandlingen kan endast uppnås med hjälp av neutronspridningsexperiment.  SANS-experiment används för kvantifiering av nano- och mikrostrukturella egenskaper inklusive mätning av den Co-rika bindefasens storlek, kornstorlek hos WC och storleken och volymsfraktionen av (V,W)Cx-gränsskikt. Den kvantitativa datan gör det möjligt för oss att dra slutsatser angående mekanismen för inhibering av kornförgrovning i V-dopade hårdmetaller vid olika V-tillsatser. Resultaten tyder på att kornförgrovningsinhiberingen i V-dopade hårdmetaller härrör från minskad rörlighet av WC/Co-gränskikt och minskad total drivkraft för förgrovning. Den komplexa karaktären av den strukturell utveckling vid sintringstemperaturer undersöks ytterligare genom in-situ SANS upp till 1500 °C. Resultaten visar att storleken och volymsfraktionen hos gränsskikten starkt beror på närvaron av bulk (V,W)Cx-utskiljningar och V-aktivitet i bindefasen.  In-situ ND-experiment under åldring av (Ti,Zr)C-baserade system ger tidsupplösta insikter i kinetiken och den strukturella utvecklingen under fasseparation vid 1600 °C under 10 timmar. Resultaten visar att sönderfallet av (Ti,Zr)C till TiC-och ZrC-rika faser kan fördröjas avsevärt genom små mängder av HfC eller NbC-tillsatser. Under sönderdelning observerades ingen förändring i gitterparametern för ZrC-rik fas. Däremot minskar gitterparametern i TiC-rik fas under sönderfallet, vilket är ett resultat av TiC-anrikning och liknar spinodalt sönderfall. Dessutom har en ny karbid i systemet (Ti,Zr,Hf,W)C designats och den har exceptionell hårdhet. Även om systemet har en blandningslucka så sker endast smärre sönderfall efter 100 timmars åldring vid 1350 °C genom bildning av (Ti,W)C-och (Zr,Hf)C-rika produkter och WC-utskiljningar. En sådan långsam sönderfallskinetik gör att karbiden bibehåller sin höga hårdhet. Sammanfattningsvis, genom att använda neutronspridningstekniker bidrar denna avhandling till en bättre förståelse av nano- och mikrostrukturutveckling i hårdmetaller och relaterade system under olika industriellt relevanta processer vid hög temperatur. Avhandlingen och bifogade artiklar vägleder även läsarna angående förberedelser, t.ex. prov och provmiljö, och dataanalys efter neutronspridningsexperiment. Avhandlingen kan därmed vara en utgångspunkt och stimulera vidare användning av neutronspridningstekniker inom hårdmetallindustrin. Stiftelsen för Strategisk Forskning (SSF): SwedNESS - Sveriges neutronforskarskola (GSn15-0008

Microstructure-mechanical property relationship of X60Mn18 steel

In the present study, the microstructure, tensile deformation behavior and mechanical property of X60Mn18 steel were investigated by means of light optical microscopy (LOM), ex-situ synchrotron-XRD and ex-situ small angle neutron scattering (SANS) as a function of the various recrystallization annealing durations (2 min and 30 min) and tensile deformation levels (0%, 25% and 50%). The ex-situ synchrotron-XRD analysis was conducted via MAUD software to reveal the microstructural properties including the phase fractions, lattice parameters, microstrain, crystallite size, stacking fault probability and dislocation density

Giant Merkel Cell Carcinoma Involving the Face

WOS: 000306638500009Merkel cell carcinoma is a rare, aggressive, malignant cutaneous tumor. It usually appears on the sun-exposed areas such as the head and neck in the elderly. A 72-year-old female patient was admitted to our clinic with the complaints of a big mass on her face. She described that the mass on her left cheek rapidly grew in three months. Her family and own medical history was unremarkable for skin cancers. On physical examination, there were no pathological findings except for a palpable submandibular lymphadenopathy. Dermatological examination revealed a giant tumoral lesion 9x9 cm in diameter, containing crusted and ulcerated areas on her left cheek Histopathological examination of the specimen obtained from the lesion showed a neoplastic infiltration consisting small, atypic cells with big, round, hyperchromatic nucleus, narrow cytoplasms, and prominent nucleoulus in some areas, showing high mitotic activity. The neoplasm, which had apoptotic bodies and necrobiosis, also invaded the full thickness of the skin, and the epidermis was very thin. In immunochemistry, CK20 was strongly positive, S100 was focally positive, and EMA was positive, while synaptophysin, chromogranin, vimentin, CD3, CD20, as well as CD45, and CD99 were all negative. Based on these findings, the patient was diagnosed as having Merkel cell carcinoma. On the systemic screening for metastases, nodular lesions in the lungs compatible with metastases were detected on computed tomography. By the consultations with plastic and reconstructive surgeons and oncologists, she was accepted as inoperable and etoposide monotherapy was administered. In this report, we aimed to underline the importance of early diagnosis while presenting a case of giant Merkel cell carcinoma which shows an aggressive progression with lung metastases. (Turkderm 2012; 46: 98-100

Very-small angle neutron scattering study on grain coarsening inhibition by V-doping of WC-Co composites

The mechanical properties of cemented carbides can be tuned by controlling WC grain coarsening and the simultaneous growth of the binder pocket size during the sintering. So far, bulk studies considering this phenomenon are scarce, but here, we report the first very-small angle neutron scattering (VSANS) study on cemented carbides. VSANS is supplemented with electron backscatter diffraction (EBSD) and the microstructural refinement by increasing V-doping (0, 0.02, 022, and 0.76 wt%) is quantified. The capability of VSANS as a non-destructive bulk probe for cemented carbides is shown, paving way for forthcoming in-situ studies

Bioactive compounds and physical attributes of Cornus mas genotypes through multivariate approaches

Cornelian cherry fruits are quite rich in bioactive compounds. Natural colour, rich flavonoids and anthocyanins and high antioxidant activity have made the fruits a natural drug. In the present study, antioxidant activity, total flavonoids and total phenolics of naturally growing 18 cornelian cherry genotypes with different phenotypic characteristics were determined. Size and shape parameters of the genotypes were also determined with the image-processing method; sphericity, elongation and shape index were calculated and shapes of two-dimensional fruit images were compared with elliptic Fourier analysis. Antioxidant activity, total flavonoid contents and total phenolic amounts of the genotypes were varied between 55.062 and 152.420 mmol TE. kg(-1), 286.40 and 2,882.80 mg QE. kg(-1), and 2,644.80 and 12,959.00 mg GAE. kg(-1), respectively. Multivariate variance analysis conducted based on physical characteristics revealed that six genotypes were different from the others. Shape analysis with Elliptic Fourier method revealed that the majority of present cornelian cherry genotypes had an oval appearance and a small portion of them had a drop-like appearance. According to discriminant analysis and Hotelling's pair-wise comparison tests, there were five different shape groups for present genotypes. A single genotype was placed into one of these groups, thus it was determined that this genotype was totally different in shape from the others

High versus Moderate Dosage of Daily and Weekly Administration of Vitamin D Supplements in the Form of Oil Drop in Nursing Home Residents

Objective: To investigate the effectiveness of daily (800 IU), weekly-moderate (5600 IU) and weekly-high (8000 IU) supplementation of Vitamin D in nursing home residents

Biochemical composition and shape-dimensional traits of rosehip genotypes

In the present study, the biochemical composition and shape and dimensional traits of 25 rosehip (Rosa canina) genotypes were investigated. The shape and dimensional traits were determined by image processing technique. Seed-propagated rosehip genotypes belonging to R. canina were collected from the natural flora of Mesudiye (Ordu) and Talas (Kayseri) districts. Antioxidant activity (39.510-72.673 mmol center dot kg(-1)), total flavonoids (287.80-1,686.20 mg quercetin equivalent (QE) center dot kg(-1)) and total phenolics (38,519.40-79,080.60 mg gallic acid equivalent center dot kg(-1)) of the genotypes exhibited large variations. Width (12.2 mm) and thickness (12.5 mm) of fruits averages were found to be close to each other. The genotypes exhibited fruit lengths between 12.0 mm and 29.5 mm. Average projected area at horizontal orientation (179.7 mm(2)) was greater than the projected area at vertical orientation (120.4 mm(2)). Sphericity average was calculated as 71.4%. According to principal component (PC) analysis, the most important dimensional traits discriminating genotypes from each other were identified as surface area, geometric mean diameter and volume. In terms of shape attributes, distinctive differences were observed in sphericity, circularity, elongation and surface closure rates (SCR) of the genotypes. According to elliptic Fourier analysis (EFA), genotypes look like a sphere. In terms of shape, there were long, spherical, flat bottomed, pointed bottomed and asymmetric-looking genotypes indicating how environment and genotype affect the fruit shape. The greatest shape variation was transverse contraction and expansion. According to the clustering analysis for shape attributes, rosehip genotypes were classified into six groups. Dendrogram, scatter plots of linear discriminant analysis and paired comparison test results put forth the shape differences of the genotype successfully

Quantification of nano-scale interface structures to guide mechanistic modelling of WC grain coarsening inhibition in V-doped hard metals

The control of tungsten carbide (WC) grain coarsening using coarsening inhibitors is considered to be one of the most important advancements for hard metals, leading to metal cutting tools with increased performance. Until now, however, the grain coarsening inhibition mechanism for effective inhibitors such as V has been elusive, posing an obstacle to material optimization. This study serves to quantify the presence of nanoscale V-W-C over a wide range of V/Co ratios by small-angle neutron scattering (SANS). The experiments help to delineate how additions of V affect the nanostructure during sintering and result in smaller WC grains. In contrast to the common view that grain coarsening inhibition originates from the presence of stable nanoscale (V,W)Cx complexions formed at the WC/Co interfaces, we show that V segregates at the WC/Co interfaces already upon a minor addition of V and brings significant coarsening inhibition. Increasing additions of V result in the formation of (V,W)Cx complexions; and above 0.76 wt% V addition, where the coverage on WC grains is complete, no further reduction in average grain size is observed. Mechanistic modelling of grain coarsening reveals that grain coarsening inhibition is governed by the reduction of interface mobilities and total driving force for coarsening

Assessment of Developmental And Radiological Long-Term Outcome of Children with Surgically Treated Midgut Volvulus

Background/aim: The aim is to evaluate the long-term outcome of asymptomatic patients who underwent surgical correction for midgut volvulus. Materials and methods: Seven patients managed surgically for midgut volvulus in the last 3 years were included. Demographic features, symptoms at presentation, diagnoses, surgical procedures, and complications were recorded. Patients were then contacted for follow-up and evaluation of long-term outcomes. General physical conditions, anthropometric parameters, feeding habits, and defecation histories were evaluated. Laboratory examinations were performed. Color Doppler ultrasonography (CDUS) was performed to evaluate blood flow in the superior mesenteric artery (SMA). Results: In total, seven patients were identified. The median age at admission was 3 days (0-90 days). Mean age at follow-up was 17 +/- 2 months. Growth parameters were normal in all cases. Four patients had low levels of ferritin and transferrin saturation. One patient had microcytic anemia. Another patient had low serum zinc level. One patient who had ileal resection had a high level of steatorrhea in stool examination. In CDUS, SMA blood flow volume was low in all cases. Peak-systolic velocity and resistance index were low in all but one case. Conclusion: Despite uneventful postoperative courses, all patients operated on for midgut volvulus showed mild laboratory changes and decreased blood flow in the SMA in long-term follow-up.WoSScopu