Steel-matrix composites are a new type of material studied at Technische Universität Bergakademie Freiberg, Germany, within a Collaborative Research Center (SFB 799) funded by German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) since 2008. After the first 4 years, the continuation was approved by DFG for another period. Thus, it is possible to continue this fundamental research on composites of metastable, austenitic steels with MgO-partially stabilized zirconia until 2016, when a final period may be applied for.
In the present special issue of Advanced Engineering Materials selected results of the first research period are presented in a comprehensive way in order to give insight into this topic. The marriage of different materials as metastable steels which have the potential of deformation-induced martensitic phase transformations (i.e., TRIP steels) and/or twinning-induced plasticity (i.e., TWIP steels) with zirconia showing a stress-assisted phase transformation opens a new window for getting attractive composite materials. We follow two different processing routes: (i) melt infiltration of liquid steel into porous ceramic preforms and (ii) powder metallurgy applying conventional as well as modern sintering techniques as spark plasma sintering. The shape of the new materials ranges from compact specimens up to filigree honeycomb structures.
The research work covers the processing technologies of the composites, the steel design including the thermo physical properties of steel melt and research on the TRIP and the TWIP effects, fundamental structure analysis of the operating deformation and damage mechanisms, the mechanical behavior under different loading conditions as highly dynamic impact loading and fatigue, as well as modeling of the processing like infiltration and of the thermodynamic phase constitution and mechanical behavior by finite element methods. Thus, a complete figure of the processing, the behavior and the modeling will be available at the end of the collaborative research center.
In the recently started second period we will also include application-relevant problems like joining with electron beam technologies as well as corrosion and corrosion protection. Thus, a total of 18 projects with more than 25 funded researchers are working together in an interdisciplinary research center. A very important subject is also the qualification of the research assistants with the aim of getting a doctorate degree completed by different soft skills.
We are grateful to the journal editors that we have the possibility to present some of our most recent results in this special issue and hope that the readers will get an impression why we are such enthusiastic in the TRIP-matrix composites.