Approaches to X-ray CT evaluation of in-situ experiments on damage evolution in an interpenetrating metal-ceramic composite with residual porosity

erpenetrating metal-ceramic composite of AlSi10Mg and an open porous alumina foam, with residual porosity is investigated for the material damage under compressive load within an X-ray CT in-situ load stage. The focus of the research is on damage detec- tion and evaluation with the commercial A vizo® software by ThermoFisher Scientific. Four different approaches are used to detect the material damage and compared afterward on their efficiency in detecting the material damage volume but not the porosity within the material. Image Stack Processing combined with different filtering techniques, as well as Digital Volume Correlation is used in this work to separate the material porosity and the material damage. For the here investigated material system with mainly spherical pores, a geometrical filter was very successful to separate porosity and damage. Nevertheless, the Digital Volume Correlation based approach showed many advantages in damage detection and turned out to be the approach of choice regarding damage onset

Approaches on self-healing of an interpenetrating metal ceramic composite

An interpenetrating metal ceramic composite (IMCC), manufactured via gas pressure infiltration of AlSi10Mg melt into a open porous Al2O3-preform, was investigated upon the ability of self-healing. A specific damage is introduced into the IMCC first. Then microstructural investigations are carried out at the damaged samples and for self-healing treated samples. The nature of the interpenetrating structure is used to heat the composite above the solidus temperature of the metallic phase and provide a shape stability by the ceramic phase to melt the metal and fill the cracks formed before. The investigation is systematically compared to the results of the undamaged samples as well as the pre-damaged samples without treatment for self-healing. The microstructural results show a change in crack geometry and therefore the possibility of self-healing. Nevertheless, open questions in process control as well as parameter- optimization require further research to achieve microstructural improvement of the healed samples above the performance of the pre-damaged ones

Numerical and Experimental Characterization of Elastic Properties of a Novel, Highly Homogeneous Interpenetrating Metal Ceramic Composite

An interpenetrating aluminum–alumina composite is presented, based on a ceramic foam manufactured via a novel slurry-based route resulting in a highly homogeneous preform microstructure in contrast to other preform techniques. The metal matrix composite (MMC) is produced by infiltrating the open-porous ceramic preform with molten aluminum at 700 °C using a Argon-driven gas pressure infiltration process. The resulting MMC and the primary ceramic foam are investigated both numerically and experimentally in terms of microstructural characteristics. In addition, the mechanical behavior of the material as well as the structural and material interactions on the microscale are investigated. To characterize the MMC regarding mechanical isotropy, elastic properties are determined experimentally via ultrasonic phase spectroscopy (UPS). A fast Fourier transform (FFT) formulation is used to simulate the complex 3D microstructure with reasonable effort based on image-data gathered from highresolution X-ray computed tomography (CT) scans of the ceramic foam as computational grid. Simulations prove that the material properties are, indeed, considered as highly homogeneous with respect to the material microstructure. A comparison with effective experimental investigations confirms these findings

Numerical and Experimental Investigation on the Self‐Healing Potential of Interpenetrating Metal–Ceramic Composites

An interpenetrating metal ceramic composite (IMCC) has been investigated regarding the potential as well as the feasibility of self-healing. Triggered by heating, cracks in the damaged composite located mainly in the Al2O3 ceramic or at the interface could be filled and closed by the liquid AlSi10Mg metal alloy. This healing procedure promises to reduce stress concentrations at crack tips and to improve the mechanical properties compared to the predamaged composite. Two different numerical approaches have been introduced to investigate this assumption and the potential of self-healed IMCCs for a best case scenario: 1) A simple 2D model to analyze the reduction of stress concentrations in front of a crack tip within the ceramic due to healing and 2) a 3D model based on CT-scan reconstructed microstructures to study how macroscopic mechanical properties can be restored depending on the amount of predamage. Further, the self-healing approach has been investigated experimentally for the same composite. Despite the fact that experimental self-healing of the investigated IMCC is only moderately feasible so far, the study shows the great potential that can still be exploited in order to extend the service life time of IMCC engineering components

Numerical and experimental investigation on the self‐healing potential of interpenetrating metal–ceramic composites

An interpenetrating metal ceramic composite (IMCC) has been investigated regarding the potential as well as the feasibility of self-healing. Triggered by heating, cracks in the damaged composite located mainly in the Al2O3 ceramic or at the interface could be filled and closed by the liquid AlSi10Mg metal alloy. This healing procedure promises to reduce stress concentrations at crack tips and to improve the mechanical properties compared to the predamaged composite. Two different numerical approaches have been introduced to investigate this assumption and the potential of self-healed IMCCs for a best case scenario: 1) A simple 2D model to analyze the reduction of stress concentrations in front of a crack tip within the ceramic due to healing and 2) a 3D model based on CT-scan reconstructed microstructures to study how macroscopic mechanical properties can be restored depending on the amount of predamage. Further, the self-healing approach has been investigated experimentally for the same composite. Despite the fact that experimental self-healing of the investigated IMCC is only moderately feasible so far, the study shows the great potential that can still be exploited in order to extend the service life time of IMCC engineering components

Thermal expansion behavior and elevated temperature elastic properties of an interpenetrating metal/ceramic composite

The thermal and elastic behavior of an interpenetrating metal ceramic composite (IMCC), consisting of ceramic foam with 74 % open porosity and an AlSi10Mg light-weight aluminum alloy was investigated at elevated temperatures. The elastic properties of the IMCC and its individual components were determined by ultrasonic phase spectroscopy and resonant frequency damping analysis (RFDA) at RT, showing a highly isotropic behavior for the IMCC. The directional elastic modulus measured at elevated temperature by RFDA decreased from about 110 GPa at room temperature to 80 GPa at 500°C. The elastic modulus temperature curve shows a clear hysteresis for the IMCC, but not for the individual components. Dilatometry experiments revealed the onset of a hysteresis effect in the CTE curve between 260 and 285°C. The hysteresis behavior could be explained by internal stress relaxation, reduction of micro voids and interfacial detachment and assigned to characteristic areas of the hysteresis curve. The associated behavior of the elastic modulus over the temperature range was investigated in detail, and the hysteresis behavior, observed for the first time in the literature was assigned and explained