To investigate the impact of various Al-Ti-B grain-refiners on solidification and grain-refining performance, a wrought aluminium alloy AA6182 was used. Three different grain-refiners from different ...manufacturers were used to establish the efficiency, i.e. contact time before casting, on the primary solidification and grain formation size. The primary solidification of α-Al grains at inoculation was observed by using thermal analysis (TA). Differential scanning calorimetry (DSC) was used in order to analyze the quality of various grain-refiners. The size of the primary grains was analyzed using optical microscopy (OM). Scanning electron microscopy (SEM) was used to estimate the size and distribution of Al3Ti and TiB2 particles in various grain-refiners and to establish the best efficiency of the investigated grain-refiners. Within 1-4 min of inoculation the smallest fine equiaxed grains were achieved when either one of the investigated grain-refiners was added. It was established, that grain-refiner A contains higher content of impurities which do not melt in the experimental temperature range made by DSC method. The most pure grain-refiner turned out to be grain-refiner B, in which the most optimal number of TiB2 particles and particle size distribution was found.
The microstructure features and hardness of AlSi9Cu3(Fe) die casting alloy
was investigated in the presence of Zr addition. The cast alloys were
undergone the solutionizing treatment 2 h at 500?C ...followed by artificial
aging at 180?C for 5 h. Optical microscopy and electron micro-analyzer were
used to study the formation of different intermetallic phases. The hardness
was tested for all samples at 25?C. The results revealed that the
intermetallic phase, based on (Al,Si)(Zr,Ti), forms when Zr is added in the
investigated alloy, while the T6 heat treatment does not influence on the
formation of Zr-bearing phase. Results also indicate that the hardness
slightly increases in the AlSi9Cu3 alloy in as-cast state when Zr is added,
while after T6 heat treatment increases by 50% in the alloy without Zr and
by 61% in the alloy with Zr addition.
nema
In the present work, the microstructure and grain refining performance of Ce
on A380 alloy have been investigated, using thermal analysis, light
microscopy with polarized light and scanning electron ...microscopy (SEM). The
purpose was to study the influence of Ce addition on the formation of the
microstructure. Ce changed the morphology of eutectic Al2Cu phase and caused
small formation of primary crystals of ?Al. Furthermore Ce phase was detected
indicating quaternary phase AlCeCuSi (Al9Ce2Cu5Si3).
nema
The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple ...thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.
Primarni cilj udrobnjevanja v aluminijevih zlitinah je zmanjšati velikost strjenih kristalnih zrn, s čimer se odpravi prisotnost velikih stebrastih zrn. Ta proces udrobnjevanja je ključen za ...izboljšanje mehanskih lastnosti in splošne učinkovitosti zlitine. Da bi dosegli odlične rezultate udrobnjevanja zrn, je bistvenega pomena uporaba visokokakovostnega udrobnilnega sredstva. To vključuje upoštevanje različnih dejavnikov, kot so ustrezno število delcev Al3Ti in TiB2, primerna oblika in velikostna porazdelitev delcev ter optimalno razmerje Ti/B. Za oceno kakovosti različnih udrobnilnih sredstev je bila izvedena raziskava z uporabo električne upornosti. Poleg tega so bile izvedene analize diferenčne vrstične kalorimetrije in mikrostrukturę za potrditev in podporo pridobljenih rezultatov. Med preiskovanimi udrobnilnimi sredstvi je najnižjo električno upornost izkazalo udrobnilno sredstvo B (Ak-3Ti-1B). Rezultat je mogoče pripisati več dejavnikom. Prvič, udrobnilno sredstvo B je imelo nizko vsebnost nečistoč, kar kaže na visoko stopnjo čistosti in kakovosti. Nečistoče, kot sta Fe in Si, lahko negativno vplivajo na učinkovitost udrobnjevanja in prispevajo k večji električni upornosti. Poleg tega je udrobnilno sredstvo B pokazalo ustrezno število in velikostno porazdelitev delcev TiB2 in Al3Ti. Prisotnost ustrezne količine teh delcev spodbuja učinkovito nukleacijo, ki je bistvena za uspešno udrobnjevanje. Velikostna porazdelitev delcev ima prav tako ključno vlogo pri zagotavljanju njihove enakomerne disperzije po zlitini, kar vodi do doslednega in učinkovitega udrobnjevanja zrn. Poleg tega je imelo udrobnilno sredstvo B optimalno razmerje Ti/B 3,6. Razmerje Ti/B je kritičen parameter, saj vpliva na nastanek in porazdelitev nukleirajočih delcev. Optimalno razmerje zagotavlja prisotnost zadostnega števila nukleirajočih delcev, kar omogoča učinkovito udrobnjevanje zrn. Nasprotno pa so druga udrobnilna sredstva pokazala večjo električno upornost. To lahko pripišemo različnim dejavnikom, kot sta povečana količina in velikost delcev TiB2 in Al3Ti ter prisotnost nečistoč, kot sta Fe in Si. Ti dejavniki lahko ovirajo proces udrobnjevanja in povzročijo večjo velikost zrn ter zmanjšano učinkovitost udrobnilnega sredstva. Poleg tega lahko prisotnost vključkov v zlitini prispeva k večji električni upornosti.
The AM60 alloy was thermodynamically examined using chemical analysis, thermodynamic calculation made by ThermoCalc program, ?in situ? thermal analysis and differential scanning calorimetry (DSC), ...whereas the microstructure constituents were confirmed using optical and scanning electron microscopy (SEM). At the eutectic temperature of 437 ?C the equilibrium solubility of Al in Mg is 12.6 wt. % Al. On the boundaries of the primary Mg grains the intermetallic compound of Al12Mg17 is precipitating according to the solvus line of the Mg-Al phase diagram. Solidification of the AM60 alloy has been investigated using ?in situ? simple thermal analysis. The investigation of solidification has been taking place by evaluation of the cooling curves in connection with metallographic examinations, differential scanning calorimetry and thermodynamic calculations. All defects, nonmetallic inclusions and intermetallic compounds that occur in investigated AM60 alloy were identified.
nema
AlCu3 alloy was examined with the triple simple thermal analysis (TETA), the simultaneous thermal analysis (STA), the computer simulation using Thermo-Calc program and with the metallographic ...analyses. The energy of solidification and melting of the primary and the eutectic phase, and the energy of the Al2Cu precipitation were determined, and these can be evidently seen from the curves of simultaneous thermal analysis.
Tlačno litje je eden od vodilnih livarskih postopkov v sodobni industriji. V primeru tlačnega litja je talina v stiku z orodjem, medtem ko pride do kemične interakcije med orodjem, izdelanim iz ...orodnega jekla, in talino. Poleg tega pride tudi do mehanske in toplotne obrabe orodij. Visoka produktivnost zahteva visoko odpornost na te dejavnike. V raziskavi smo uporabili vzorce iz jekel UTOP MO1 in RAVNEX HD, da bi preverili njihovo odpornost proti obrabi v aluminijevih zlitinah Al99,7 in AlSi12. S tem namenom je bila izdelana laboratorijska naprava za testiranje dveh različnih orodnih jekel v dveh različnih aluminijevih zlitinah pri dveh različnih temperaturah 4 ure pri 75 vrtljajih na minuto. Posledica interakcije je rast reakcijske plasti, ki se tvori iz treh ali štirih plasti. Odpornost orodnega jekla UTOP MO1 je boljša v staljeni aluminijevi zlitini AlSi12 kot v Al99,7, medtem ko je obrabna orodnega jekla RAVNEX HD v aluminijevih zlitinah veliko slabša. Debelina interakcijskega sloja se poveča z naraščajočo temperaturo.
Standardni materiali ne izpolnjujejo strogih zahtev za kompleksne aplikacije. Članek obravnava modeliranje inovativnih aluminijevih zlitin z boljšimi lastnostmi za visokotemperaturne aplikacije. Za ...analizo vpliva dodatka cirkonija in molibdena na strjevanju zlitine Al-Si-Mg-Mn, smo uporabili termodinamične izračune, enostavno termično analizo in diferencialno kalorimetrijo. Optična mikroskopija in elektronska vrstična mikroskopija z energijsko disperzijsko spektroskopijo sta služili za določanje razvoja mikrostrukture preiskovanih zlitine. Analizirali smo kemično sestavo, vrsto in količino nastalih faz, preučili ravnotežne in neravnotežne procese ter značilne temperature strjevanja za laboratorijske in industrijske aluminijeve zlitine. Ko smo v zlitino dodali cirkonij, se je izoblikovala nova igličasta faza. Molibden v zlitini je vključen v fazo AlFeMnSi, pri čemer v nekaterih primerih delno zamenja železo in oblikuje novo fazo AlFeMnMoSi z drugačno morfologijo bolj zaokrožene kitajske pisave.
There is a shortage of psychiatrists worldwide. Within Europe, psychiatric trainees can move between countries, which increases the problem in some countries and alleviates it in others. However, ...little is known about the reasons psychiatric trainees move to another country.
Survey of psychiatric trainees in 33 European countries, exploring how frequently psychiatric trainees have migrated or want to migrate, their reasons to stay and leave the country, and the countries where they come from and where they move to. A 61-item self-report questionnaire was developed, covering questions about their demographics, experiences of short-term mobility (from 3 months up to 1 year), experiences of long-term migration (of more than 1 year) and their attitudes towards migration.
A total of 2281 psychiatric trainees in Europe participated in the survey, of which 72.0% have ‘ever’ considered to move to a different country in their future, 53.5% were considering it ‘now’, at the time of the survey, and 13.3% had already moved country. For these immigrant trainees, academic was the main reason they gave to move from their country of origin. For all trainees, the overall main reason for which they would leave was financial (34.4%), especially in those with lower (<500€) incomes (58.1%), whereas in those with higher (>2500€) incomes, personal reasons were paramount (44.5%).
A high number of psychiatric trainees considered moving to another country, and their motivation largely reflects the substantial salary differences. These findings suggest tackling financial conditions and academic opportunities.
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