Nickel- and Cobaltbase superalloys

Effect of climb on dislocation mechanisms and creep rates in gamma’-strengthened Ni base superalloy single crystals: A discrete dislocation dynamics study

Creep of single-crystal superalloys is governed by dislocation glide, climb, reactions and annihilation. Discrete three-dimensional (3D) dislocation dynamics (DDD) simulations are used to study the evolution of the dislocation substructure in a gamma/ gamma’ microstructure of a single-crystal superalloy for different climb rates and loading conditions. [more]

Effect of ruthenium on the precipitation of topologically close packed phases in Ni-based superalloys of 3rd and 4th generation

The precipitation of topologically close packed (TCP) phases is detrimental for the high temperature strength of high refractory Ni-based superalloys. The beneficial influence of Ru with respect to this so called instability is nowadays well accepted. [more]

On the origin of creep dislocations in a Ni-base, single-crystal superalloy

This project deals with the origin of creep dislocations in a Ni-base, single crystal superalloy subject to creep at an intermediate stress and temperature. [more]

Study of hydrogen embrittlement by using multi-scale and spatially resolved hydrogen mapping in a Ni-Nb model alloy and in alloy 718

In this project we investigate the hydrogen distribution and desorption behavior in an electrochemically hydrogen-charged binary Ni-Nb model alloy. The aim is to study the role of the delta phase in hydrogen embrittlement of the Ni-base alloy 718. [more]

Precipitation and crack formation behaviour of Ni-based-superalloys

Ni-based superalloys are high-temperature materials employed e.g. in turbines. They gain their high strength by precipitation hardening. The unique thermal history encountered by the material during LAM, which includes rapid cooling from the melt, cyclical re-heating and/or an elevated processing temperature due to preheating, influences the number density and size distribution of the precipitates. For the same reason, unwanted defects, such as hot cracks, can occur in the material. [more]

Recrystallization studied with indentation tests and coupled crystal plasticity and cellular automaton simulations

In this project an integrated simulation strategy for studying primary static recrystallization was developed and applied to a single-crystal nickel-base superalloy. By using a crystal plasticity finite element approach, the driving force for nucleation and grain growth around a Brinell-type indent was modeled. [more]