Crystallization kinetics of the bulk-glass-forming Pd43Ni10Cu27P20 melt

The crystallization of undercooled Pd43Ni10Cu27P20 melts is studied under isothermal conditions and at constant heating and cooling rates. Investigations are carried out by fluxing the melt with B2O3 and without any fluxing material. The isothermal experiments allow us to determine the complete time–temperature-transformation diagram with a minimum crystallization time of about 200 s for the fluxed melt and about 130 s for the unfluxed Pd43Ni10Cu27P20 melt. The results of the experiments at constant cooling and heating rates are summarized in a continuous heating and cooling diagram. The critical cooling rate for the fluxed alloy is determined to be 0.09 K/s, whereas the critical heating rate is 6 K/s. For the unfluxed Pd43Ni10 Cu27P20, 0.4 and 9 K/s are found, respectively. This alloy exhibits the most sluggish crystallization kinetics of all metallic systems known so far

Repeated crystallization in undercooled Zr41Ti14Cu12Ni10Be23 liquids

Isothermal crystallization studies are performed on Zr41Ti14Cu12Ni10Be23 melts. Undercooling experiments are carried out repeatedly at 907, 860, and 750 K. The scattering of the time to reach the onset of crystallization is investigated. Results from experiments performed at 907 K show a large scatter of the onset time of crystallization. For the experiments carried out at 860 and 750 K, scattering of the onset time is two orders of magnitude smaller. These results indicate that, at high temperatures, the crystallization is governed by the time scale of the statistical nucleation events. At low temperatures, the crystallization is controlled by diffusion, resulting in a well-defined onset time for crystallization

Loan supply in Germany during the financial crisis

Distinguishing pure supply effects from other determinants of price and quantity in the market for loans is a notoriously difficult problem. Using German data, we employ Bayesian vector autoregressive models with sign restrictions on the impulse response functions in order to enquire the role of loan supply and monetary policy shocks for the dynamics of loans to non-financial corporations. For the three quarters following the Lehman collapse, we find very strong negative loan supply shocks, while monetary policy was essentially neutral. Nevertheless, the historical decomposition shows a cumulated negative impact of loan supply shocks and monetary policy shocks on loans to non-financial corporations, due to the lagged effects of past loan supply and monetary policy shocks. However, these negative effects on loans to non-financial corporations are overcompensated by positive other shocks, which implies that loans developed more favorably than implied by the model, over the past few quarters. --Loan supply,Bayesian VAR,sign restrictions

Pronounced asymmetry in the crystallization behavior during constant heating and cooling of a bulk metallic glass-forming liquid

The crystallization behavior of the supercooled bulk metallic glass-forming Zr41Ti14Cu12Ni10Be23 liquid was studied with different heating and cooling rates. A rate of about 1 K/s is sufficient to suppress crystallization of the melt upon cooling from the equilibrium liquid. Upon heating, in contrast, a rate of about 200 K/s is necessary to avoid crystallization. The difference between the critical heating and cooling rate is discussed with respect to diffusion-limited growth taking classical nucleation into account. The calculated asymmetry of the critical heating and cooling rate can be explained by the fact that nuclei formed during cooling and heating are exposed to different growth rates

Multi-Objective Optimization of an Aerodynamic Feeding System Using Genetic Algorithm

Considering the challenges of short product life cycles and growing variant diversity, cost minimization and manufacturing flexibility increasingly gain importance to maintain a competitive edge in today’s global and dynamic markets. In this context, an aerodynamic part feeding system for high-speed industrial assembly applications has been developed at the Institute of Production Systems and Logistics (IFA), Leibniz Universitaet Hannover. The aerodynamic part feeding system outperforms conventional systems with respect to its process safety, reliability, and operating speed. In this paper, a multi-objective optimisation of the aerodynamic feeding system regarding the orientation rate, the feeding velocity, and the required nozzle pressure is presented

Batch-Oriented Setting Time Optimisation in an Aerodynamic Feeding System

The change of conditions for production companies in high-wage countries is characterized by the globalization of competition and the transition of a supplier´s to a buyer´s market. The companies need to face the challenges of reacting flexibly to these changes. Due to the significant and increasing degree of automation, assembly has become the most expensive production process. Regarding the reduction of production cost, assembly consequently offers a considerable rationalizing potential. Therefore, an aerodynamic feeding system has been developed at the Institute of Production Systems and Logistics (IFA), Leibniz Universitaet Hannover. This system has been enabled to adjust itself by using a genetic algorithm. The longer this genetic algorithm is executed the better is the feeding quality. In this paper, the relation between the system´s setting time and the feeding quality is observed and a function which enables the user to achieve the minimum of the total feeding time is presented

Employee Qualification by Digital Learning Games

Global competition and individual customer requirements generate challenges for manufacturing companies. To cope with these challenges, companies require an increased level of flexibility. In the first place, this flexibility has to be provided by the employees, as they are one of the key success factors for mastering change. An essential prerequisite for this is a high level of employee qualification across all areas of the company. The learning factories approach has garnered particular attention in recent years as a playful and efficient way of learning the principles and methods of processes improvement. The drawbacks of this method include the limited, non-holistic perspective of each trainee as well as the non-recurring knowledge transfer. Moreover, this kind of qualification requires the trainees to be in the same place at the same time. These downsides can be successfully countered by supplementing learning factories with a digital learning component depicting the learning environment, as digital learning will enable individual learning routes for all trainees and is accessible at all times and all places. This paper serves to outline the idea of serious learning by using digital learning games along with the attendant benefits. Over and beyond this, it also presents a digital learning game for teaching specific lean production methods. © 2017 The Author