Time–temperature–transformation diagram and microstructures of bulk glass forming Pd40Cu30Ni10P20

Isothermal crystallization studies were performed on the bulk glass forming alloy Pd40Cu30Ni10P20 in the undercooled liquid region between the glass transition and liquidus temperature, resulting in a complete time–temperature–transformation (TTT) diagram for crystallization. The TTT diagram shows a typical "C" shape with the nose at 50 s and 680 K. Assuming steady state nucleation and a diffusion-controlled growth rate, the TTT diagram was successfully fit over the entire range of the measurement. The microstructure after isothermal crystallization shows a modulation in Cu and P for all degrees of undercooling. The primary solidified phase is Cu3Pd, which forms distinct dendrites at low undercooling. From additional constant cooling experiments, the critical cooling rate to bypass crystallization was determined to be 0.33 K/s

The structure of the distributions of cash flows and discount rates in multiperiod valuation problems

In capital budgeting problems future cash flows are discounted using the expected one-period returns of the investment. In this paper we relate this approach to the assumption that markets are free of arbitrage. Our goal is to uncover implicit assumptions on the set of cash flow distributions that are suitable for the capital budgeting method. Our results are twofold. First we obtain that for deterministic cost of capital the set of admissible cash flow distributions is large in the sense that no particular structure of the evolution of the distributions is implied. We give stylized examples that demonstrate that even strong assumptions on the return distributions do not restrain the shape of the cash flow distributions. This shows that Fama’s assertion that the distributions of one-period single returns become more and more skewed cannot be generalized to multiperiod budgeting problems. Secondly, in a subsequent analysis we characterize the cash flow distributions under the additional assumption of a deterministic dividend yield. In this case a linear relationship between returns and cash flows obtains

Semi-subjektive Bewertung mit μ-σ-Nutzenfunktionen

Seit über einem Jahrzehnt beschäftigt sich Lutz Kruschwitz mit Fragen der Unternehmensbewertung. Seine diesbezüglichen Veröffentlichungen sind bis auf eine Ausnahme in Zeitschriften und Festschriften erschienen. Charakteristisch für die Herangehensweise von Lutz Kruschwitz ist eine sehr starke Modellorientierung; empirische oder rechtliche Fragestellungen haben ihn eher am Rande beschäftigt. Insbesondere kann man sagen, dass Lutz Kruschwitz einer der nicht zahlreichen deutschen Autoren ist, die sich intensiv mit der Einbeziehung von Steuern in der Finanzwirtschaft und speziell der Unternehmensbewertung auseinander gesetzt haben. Immer dann, wenn man sich mit diesem Thema beschäftigt, steht man angesichts des ausufernden deutschen Steuerrechts vor einem Dilemma: Sollen die Steuern detaillierter beschrieben werden, damit das Modell wenigstens einen Hauch von Nähe zum geltenden Recht aufweist – dann aber wird das Modell häufig “unberechenbar”, so dass Autoren gern eine sichere Umwelt oder nur eine Periode unterstellen. Oder soll das Modell den Gegebenheiten der Unternehmensbewertung angepasst werden, bei der wir typischerweise unsichere Cashflows und mehrere Perioden beobachten – dann aber lassen sich viele Details des Steuerrechts nur sehr schwer oder gar nicht abbilden. Man kann mit Fug und Recht sagen, dass es Lutz Kruschwitz in der Vergangenheit wie nur Wenigen gelungen ist, hier einen Mittelweg zu finden, der sich als sehr fruchtbar erwiesen hat: Seine lange Veröffentlichungsliste spricht für sich. Kürzlich ist zwischen Kürsten (2002) und Schwetzler (2002) eine Diskussion entbrannt, in der es unter anderem um die Frage ging, ob sich die Methode der Diskontierung von Sicherheitsäquivalenten mit risikolosen Zinssätzen entscheidungstheoretisch fundieren lässt. Kürsten wies nach, dass im Rahmen des subjektiven Ansatzes eine solche Fundierung allenfalls dann gelingt, wenn man dem Bewerter Risikoneutralität attestiert. Daraus wurde der Schluss gezogen, dass die Sicherheitsäquivalenz–Methode keine entscheidungstheoretisch akzeptable Grundlage besitzt: Die Idee, überhaupt mit Sicherheitsäquivalenten zu arbeiten, beruht nach allgemeinem Verständnis auf der Voraussetzung, dass der Unternehmensbewerter risikoavers ist und nicht etwa Risikoneutralität an den Tag legt. Lutz Kruschwitz hat sich mit einem Beitrag zu dieser Fragestellung geäußert. Gemeinsam mit Andreas Löffler konnte er nachweisen, dass im klassischen Erwartungsnutzenkalkül unter gewissen, aber eben sehr strengen Voraussetzungen eine Anwendung des Sicherheitsäquivalentkalküls gerechtfertigt ist. In dieser Arbeit wollen wir untersuchen, ob sich diese Voraussetzungen auch auf den Fall des in der Finanzwirtschaft stärker verbreiteten Erwartungswert-Varianz-Kalküls übertragen lassen. Wie die Intuition es erwarten lässt, werden wir erfolgreich sein

Grain-size dependence of intergranular magnetic correlations in nanostructured metals

Magnetic small-angle neutron scattering experiments were performed on nanostructured Fe, Co and Ni samples of varying grain size, produced by inert-gas condensation. The experiments show that the spontaneous spatial magnetic correlations forming in zero-field extend over many individual grains. These correlations depend strongly on grain size. In Fe, they have a minimum at a grain size of around 35 nm and increase sharply for smaller grain sizes. The crossover occurs at grain sizes comparable with L_(crit) = πδ, where δ is the bulk domain-wall width. For grain sizes below L_(crit), the results are explained on the basis of the random-anisotropy model, which takes into account that the magnetic alignment between the grains competes with the anisotropies of the individual grains. Above L_(crit), where domain walls can form within one grain, the magnetization direction corresponds to the anisotropy direction varying from grain to grain, and the magnetic correlation length increases approximately linearly with grain size. Furthermore, the measurements on Fe, Co and Ni show that the spatial magnetic correlations measured by SANS are always larger than L_(crit). This is in agreement with results of theoretical studies showing that nonuniform magnetization configurations can only exist in grains with sizes D > L_(crit)

Stick-slip dynamics and recent insights into shear banding in metallic glasses

Despite extensive research, the understanding of the fundamental processes governing yielding and plastic flow in metallic glasses remains poor. This is due to experimental difficulties in capturing plastic flow as a result of a strong localization in space and time by the formation of shear bands at low homologous temperatures. Unveiling the mechanism of shear banding is hence key to developing a deeper understanding of plastic deformation in metallic glasses. We will compile recent progress in studying the dynamics of shear-band propagation from serrated flow curves. We will also take a perspective gleaned from stick-slip theory and show how the insights gained can be deployed to explain fundamental questions concerning the origin, mechanism, and characteristics of flow localization in metallic glasse

Concentration and temperature dependence of decomposition in supercooled liquid alloys

Small-angle neutron scattering experiments were performed on the bulk amorphous alloy Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) (Vit1®, subscripts indicate at.%) and on other alloys, where the (Zr,Ti) and (Cu,Be) contents were varied by following the line in composition space connecting Vit1 and Zr_(46.8)Ti_(8.2)Cu_(7.5)Ni_(10)Be_(27.5) (Vit4®). The small-angle neutron scattering data of the samples, annealed at temperatures between 603 K and 663 K, show interference peaks, giving evidence for spatially correlated arrangements of inhomogeneities. The Q values of the interference peaks, Q_(max), decrease with increasing annealing temperature Ta and, at a given annealing temperature, with composition following the connecting line from Vit1 to Vit4. Down to the glass transition temperature T_g, the data follow a relation 1/L^2 ∝ (T_s – T_a) as predicted by the linearized Cahn theory, with L = 2π /Q_(max) the characteristic wavelength of the decomposition and T_s the apparent spinodal temperature. Below T_g, a different behavior is observed, which may be either due to a change in atomic diffusion or due to an insufficient relaxation of the samples

Metastable quasicrystal-induced nucleation in a bulk glass-forming liquid

This study presents a unique Mg-based alloy composition in the Mg-Zn-Yb system which exhibits bulk metallic glass, metastable icosahedral quasicrystals (iQCs), and crystalline approximant phases in the as-cast condition. Microscopy revealed a smooth gradual transition from glass to QC. We also report the complete melting of a metastable eutectic phase mixture (including a QC phase), generated via suppression of the metastable-to-stable phase transition at high heating rates using fast differential scanning calorimetry (FDSC). The melting temperature and enthalpy of fusion of this phase mixture could be measured directly, which unambiguously proves its metastability in any temperature range. The kinetic pathway from liquid state to stable solid state (an approximant phase) minimizes the free-energy barrier for nucleation through an intermediate state (metastable QC phase) because of its low solid- liquid interfacial energy. At high undercooling of the liquid, where diffusion is limited, another approximant phase with near-liquid composition forms just above the glass-transition temperature. These experimental results shed light on the competition between metastable and stable crystals, and on glass formation via system frustration associated with the presence of several free-energy minima

Age, origin and palaeoclimatic implications of peri- and paraglacial boulder-dominated landforms in Rondane, South Norway

Boulder-dominated landforms of periglacial, paraglacial and related origin constitute a valuable, but often unexplored source of palaeoclimatic and morphodynamic information. The timing of landform development initiation and its subsequent stabilization can be linked to past climatic conditions offering the potential to reconstruct cold climatic periods. In this study, Schmidt-hammer exposure-age dating (SHD) was applied to a variety of boulder-dominated landforms (sorted stripes, blockfield, rock-slope failure, paraglacial alluvial fan) in Rondane, eastern South Norway for the first time. On the basis of old and young control points a regional SHD calibration curve was established and successively utilized for the calculation of surface exposure ages for individual landforms. The chronological investigation of development and stabilization of the respective landforms permitted an assessment of Holocene climate variability in Rondane and its impact on overall landform evolution. Our obtained SHD age estimates ranged from 11.44 ± 1.22 ka (ST-D2) to 4.09 ± 1.51 ka (AF1) showing their inactive and relict character. Most surface exposure ages for sorted stripes clustered between 9.88 ± 1.35 ka and 9.25 ± 1.21 ka, hence indicating stabilization during the late stage of the Erdalen Event or shortly thereafter. It is inferred that the blockfield formed prior to the Last Glacial Maximum, was protected by cold-based ice throughout glaciation and shortly reactivated during the Erdalen Event only to subsequently becoming inactive. The surface exposure age of a rock-slope failure (7.58 ± 0.73 ka) falls into the early phase of the Holocene Thermal Maximum (HTM, ~8.0–5.0 ka). This indicates permafrost degradation and/or increasing hydrological pressure negatively influencing slope stability. The paraglacial alluvial fan with its four subsites yielded ages between 8.73 ± 1.63 ka and 4.09 ± 1.51 ka. The old exposure ages point to fan aggradation following regional deglaciation due to paraglacial processes, whereas the younger ages can be explained by increasing precipitation during the onset neoglaciation at ~4.0 ka. Our results underline the importance of meltwater for the activation of periglacial landforms in a continental climate and indicate that the Erdalen Event and immediately following onset of the HTM had major impact on landscape evolution in Rondane. Our obtained surface exposure ages from boulder-dominated landforms in Rondane give important insights into the local palaeoclimatic variability during the Holocene.publishedVersio

Thermodynamic Assessment of the Sn-Ti System

Summary.: The knowledge of phase equilibria and thermodynamic properties in the ternary Cu-Sn-Ti system is of technical importance for active brazing filler metals. Thermodynamic descriptions of the binary systems Cu-Ti and Cu-Sn are well established. In this work a self-consistent thermodynamic description of the Sn-Ti binary system has been obtained by fitting critically reviewed thermochemical and phase diagram data. The newest and most consistent lattice stability has been used, and all the intermetallic phases and recent experimental information have been taken into account. The equilibrium measurement on the Sn-rich side and more experimental thermodynamic properties are required for a better thermodynamic description of this system. The evaluated thermodynamic description of the Sn-Ti binary system will serve as part of the thermodynamic database for Cu-Sn-Ti brazing alloy