EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The interaction between precipitation and deformation in aluminium alloys can profoundly affect microstructure and hence properties. Deformation is observed generally to have an accelerating effect on the precipitate evolution processes of nucleation, growth, and coarsening. This acceleration is due to the interaction of deformation induced defects, such as dislocations and vacancies, with...

Precipitation hardening is the key of the mechanical properties for 6xxx series Aluminium alloys. The precipitation sequence is complex and dependent of the alloy composition, particularly on the Mg/Si ratio. A compositionally-graded alloy is obtained with high-temperature compaction using Spark Plasma Sintering on Al-Si and Al-Mg model alloys atomised powders. The different stages of the...

6XXX alloys (AlMgSi) are of great importance for the automotive industry and lightweight design. Currently, more than 100 different compositions (different levels of alloying elements, different magnesium:silicon ratios, trace elements) of the alloy 6082 are known. In this study, quench rates between 1 and 200 K/s were applied to study the effect on mechanical properties and microstructure....

The Al-6XXX alloys are widely used in automotive applications for their high strength to weight ratio. The desired properties are achieved by precipitate hardening through the process of artificial aging at elevated temperatures. However, these alloys undergo natural aging at room temperature which is undesirable, and a mechanistic understanding of the early stages of precipitation in natural...

Composition graded AlMgSi wires were achieved with a to a two-step process. A composite made of 1370AA inserted in a 6201AA tube was first cold drawn to obtain appropriate mechanical bounding and then annealed at 500°C to achieve a composition gradient along the wire diameter. These diffusion gradients were estimated by nano-hardness profiles and a good agreement with theoretical prediction...

Heat-treatable aluminium (Al) alloys obtain their strength from the nucleation of precipitates during artificial aging. The thermomechanical history of the alloy determine the type of precipitate phase that nucleate, their interface plane and their distribution. If the alloy is stored at room temperature after solution heat treatment, the hardness increases in time due to the formation of...

The talk brings together two areas of research: the mechanical behavior of nano-structured materials with a grain-size gradient and the plastic instability in metal alloys, known as the Portevin-Le Chatelier (PLC) effect. The treatment of the surface by hyper-deformation processes locally increasing the dislocation density and/or forming a fine-grained layer has proven its effectiveness in the...

Natural aging of Al–Mg–Si alloys is a complex process, which is not fully understood yet. Nonetheless, it is widely known that for the EN AW6082 alloy natural aging has a negative effect. For the alloy EN AW6060, however, natural aging was assumed to have a beneficial influence on the hardening potential. Contradicting these assumptions, our studies showed that not only the type of alloy but...

The Portevin-Le Chatelier (PLC) effect describing unstable plastic flow in alloys is an exceptional example of self-organization phenomena in plasticity. Its dynamics stems from the mechanism associated with nonmonotonous behavior of the strain-rate sensitivity of stress, negative in a strain-rate interval allowing for dynamic strain ageing of dislocations by solutes. If the motion of all...

An important aspect of formability of Al sheet material in the automotive industry is the bendability without degradation of the surface quality. So far, microstructure, texture, the distribution of primary and secondary particles as well as these properties´ homogeneity over the sheet cross section are known as factors influencing the formability of Al-sheets. Recent studies for example...

The demands from industry and daily live have required the development of structural materials. For example, the heat-resistant Al alloys are expected for the improved performance at higher temperatures (≥300℃) due to their lower density and reasonable cost. However, the traditional heat-resistant Al alloys (i.e., Al-Si, Al-Cu) can only sustain at 250℃ currently, because the rapid diffusion of...

The mechanical properties of commercial Al-Fe-Si alloys are influenced by the materials microstructure and microchemistry. In this work, the variation of alloying elements distribution, microstructure (e.g. grain size; dendritic arm spacing) and electrical conductivity across an AA 8079 DC-ingot were investigated. Furthermore, the effects of various experimental homogenization practices on the...

Fragmentation of cube grains during rolling is of interest because their recrystallization advantage decreases when cube is misoriented at least 10 – 15° from its exact orientation. Thus, understanding evolution of cube in-grain microtexture and finding processing conditions promoting cube splitting into subdomains is of great importance.
The influence of crystallographic orientations of...

Production and machining of titanium alloys are difficult as it involves a complex combination of high loading and rapid temperature evolution. In addition, due to the contact between the cutting tool and the material, the temperature can locally reach 800 °C and above. Consequently, understanding the phenomena behind the phase transformation during machining is scientifically crucial toward...

Recently, TRIP/TWIP effects causing high ductility due to martensitic transformation (TRIP) or twinning (TWIP) during loading were found to take place in finely tuned metastable β Ti alloys. These effects, well known from steels, are present in alloys that are in the proximity to β -> α” martensitic transformation after quenching. Typically, such alloys exhibit high ductility and very...

A physical-based model is developed to describe the microstructure transformations that occur during the processing of titanium alloys. The evolution of the microstructure during hot deformation is fully coupled with the phenomena of static recrystallisation and grain coarsening that occur during annealing. Static and dynamic recovery and continuous dynamic recrystallisation are considered as...

In the present study, the effect of cold rolling and subsequent annealing on the microstructure and mechanical properties of metastable β Ti-10V-2Fe-3Al (Ti-1023) and Ti-5Al-5Mo-5V-3Cr (Ti-5553) alloys have been investigated. Room temperature cold rolling have been conducted on the alloys (5 mm3 samples). A thickness reduction up to 43% and 45%, respectively for Ti-1023 and Ti-5553 have been...

A physical-based model is implemented as a subroutine and used in FE simulations to predict the microstructure evolution during hot deformation and annealing of Ti alloys. During hot deformation, the material undergoes dynamic recovery of alpha and beta phases by forming new low angle grain boundaries, followed by continuous dynamic recrystallization. The microstructure evolves via static...

Diverse pathways of {332}<113>β mechanical twinning and stress induced martensitic transformation (BCC-Orthorhombic) were studied in a metastable beta Ti-12Mo alloy, which presents Transformation Induced Plasticity (TRIP) / Twinning Induced Plasticity effect. This work aims to clarify the pathways involved in primary and secondary transformations under external tensile stress, such as the...

One of the most critical issues in titanium metallurgy has been and remains the impact of interstitial elements and specifically oxygen on mechanical properties of titanium alloys. In these materials, oxygen is indeed known to induce a strong hardening effect combined to a severe decrease of the elongation at fracture. This embrittlement has been interpreted, until now, as a consequence of the...

Among the various significant questions affecting titanium metallurgy, the effect of interstitials, more specifically oxygen, on the (mechanical) properties of titanium alloys remains one of the most critical issues. For decades, oxygen has been considered as a detrimental element, leading to drastic embrittlement. However, there is still an important lack of knowledge on underlying mechanisms...

α+β-TiAl6V4 alloy is the most important titanium alloy for aerospace applications [1,2]. Depending on the thermo-mechanical processing route, a wide range of microstructures can be achieved which differ in proportion and arrangement of the α- and β-phase and the type of transformed β-phase. The microstructures in turn have a decisive effect on the resulting mechanical properties [3]. Since...

Metal-based additive manufacturing (AM) represents a paradigm change which will revolutionize the manufacturing across multiple industries such as the aerospace, biomedical and automotive sectors. However, today only a few alloys are compatible with AM. Most of those being used were developed for other manufacturing processes such as casting and forging processes where the mechanical...

Recent work in the field of magnesium alloy development for sheets has successfully been targeted at improving sheet formability. On the basis of such alloys, a lightweight Passat decklid prototype was fully developed and tested and Volkswagen, highlighting the benefits of such novel sheet alloys with regards to reducing their processing complexity in an automotive production context. The...

Dilute Mg-Zn-Y alloys prepared by the consolidation of rapidly solidified (RS) ribbons are characterized by complex microstructure with elongated worked and dynamically recrystallized grains with an overall average grain size about 800 nm containing dispersive Zn- and Y-rich stacking faults (SFs). In order to optimize performance of alloys, the influence of both amount of the alloying elements...

Light metals show an ever-increasing importance in modern society, especially in everyday applications such as various mobility aspects or consumer electronics. The lightest of all structural metals in use, magnesium and its alloys, has received growing attention by the scientific community and industry alike. While the industrial applications are still centered on cast products, the...

Magnesium alloys are of interest for space applications. Their low density would be beneficial to substitute aluminium in many aerospace structure applications, depending on the exact stiffness and load-bearing requirements. However, magnesium alloys are more challenging to process than aluminium. Advanced manufacturing technologies are required to allow broadening the range of applications...

The present study investigates the thermal stability of the microstructure of the rapidly solidified ribbon-consolidated Mg97.94Zn0.56Y1.5 alloy. In the as solidified state, the material has a very fine grain structure with an average grain size of around 900 nm. Moreover, dispersive Zn- and Y-rich stacking faults segregated in basal planes can be observed in the microstructure. The alloy is...

Agata Kulig1, Haneen Daoud1, Johannes Weiser2, Uwe Glatzel1,3
1 Neue Materialien Bayreuth GmbH, Gottlieb-Keim-Str. 60, 95448 Bayreuth, Germany
2 Evobeam GmbH, Am Hofgut 5, 55268 Nieder-Olm, Germany
3 Metals and Alloys, University of Bayreuth, Prof.-Rüdiger-Bormann-Str. 1, 95447 Bayreuth, Germany

Abstract
Titanium (Ti) based lightweight alloys are widely known in aerospace and medical...

The HORIZON2020 project "ENSUREAL" is developing a modernized version of the Pedersen process for production of alumina. The process counters challenges in raw material availability, energy availability, CO2 emissions and sustainability. European universities, institutes, technology partners, metal producers, fertilizers and plant suppliers cooperate to consider newest technologies, research...

In this ever-changing world the automotive industry, due to the European requirements related with the greenhouse gases emissions, the efficiency in the use of resources or sustainable transportation, has many projects with the aim of finding new materials.
Among the metallic material, aluminium is the third most abundant element in the earth crust and considering the low density and the...

In view of global warming, the reduction of greenhouse emissions has become a central topic for the transportation sector. In this context, the development of light metals is attracting attention for structural applications. Nanoparticle reinforced metal composites are a promising solution due to potentially excellent mechanical properties and low density. However, experimental results fall...

The study investigates the crushing behaviour of the open-cell aluminium foam by means of experimental testing and numerical simulations. For this purpose, a wide range of quasi-static and dynamic compression experiments at different velocities were performed. Conventional Split Hopkinson Pressure Bar (SHPB) are limited by the maximal axial strain, defined by the length of the specimen and...

Selective laser melting (SLM) technology is promising to fabricate complex-shaped metal components,especially light-weight aluminum (Al) alloy. Facing the grow requirement of thermal stability for applications in aviation and aerospace at high temperatures, the poor thermal stability of Al alloy needs to be improved. Thus, in this study, we developed a novel heat-resistant eutectic Al-Fe-Ni...

The 7XXXAl alloys are extensively used as structural components in the aerospace and automotive industries due to their higher strength and lower density.The precipitation behaviors and mechanical properties of the slow-quenched 7085Al alloy subjected to various aging treatments were studied by multi-scale microstructural and mechanical properties characterization techniques. There were coarse...

"The solidification behavior of a eutectic AlCu specimen is investigated via in situ scanning transmission electron microscope (STEM) experiments. Solidification conditions are varied by imposing various cooling rates via a micro-electro-mechanical system (MEMS) based membrane. The methodology allows the use of material processed by a melting and casting route close to industrial...

In this study, rapid solidification of single micro-sized AlSi12 (mass%) particles of various diameters has been investigated via differential fast scanning calorimetry (DFSC), employing cooling rates from 100 K/s to 90,000 K/s. Based on nucleation undercooling and on microstructure analysis of rapidly solidified single particles under controlled cooling rates, two different heterogeneous...

With the emergence of new manufacturing routes, leading to highly heterogeneous microstructures and/or geometrically complex components, there is a need for advanced electrochemical characterization of light metal degradation at the micro- and nanoscale to efficiently predict their durability.
The scanning electrochemical nanocapillary (SEN) technique allows assessing, in the sub-micrometer...

Zr-containing dispersoids act as barriers for grain boundaries movement to hinder recrystallization in aluminum alloys. However, they have a non-uniform distribution and small volume fraction, making it challenging to characterize their features in terms of size, volume fraction, and specific surface. The present work is about to answer the question: “is it possible to employ the Small-Angle...

During heating of Al alloys, typically a sequence of precipitation and dissolution reactions occurs and the single reactions superimpose. Differential scanning calorimetry (DSC) is one common technique to analyse the kinetic development of precipitation and dissolution in Al alloys, but the superposition of the exothermal precipitation and endothermal dissolution reactions complicates the DSC...