Metal-Matrix Composites: Analysis, Modeling, Observations and Interpretations: Marvels of Microstructure
Sponsored by: TMS Structural Materials Division, TMS: Composite Materials Committee
Program Organizers: Srivatsan Tirumalai; Yuzheng Zhang, Gamma Alloys; William Harrigan, Gamma Alloys
Monday 8:00 AM
February 24, 2020
Room: 31A
Location: San Diego Convention Ctr
Session Chair: William Harrigan, Gamma Alloys
8:00 AM Invited
Microstructure, Interfaces and Mechanical Properties of Nano Composites Manufactured in Solid State: Ramasis Goswami1; Alex Moser1; 1Naval Research Laboratory
B4C is the lightest among armor grade ceramic materials, with the highest compressive strength. In defense applications, there is significant interest in lightening vehicle and personnel loads by replacing current armor with lighter materials such as B4C. Considerable efforts have been made to make composite materials to enhance the specific strength of metals and alloys by adding B4C particles. It was realized the ceramic/metal interface plays a vital role in enhancing the strength of the composite materials. Using transmission electron microscopy (TEM), we investigate different ceramic/metal interfaces, such Al/B4C, Ni/B4C and Fe/B4C, processed in the solid state at relatively high pressure. We demonstrate the interface cohesion and mechanical properties have been significantly improved as a result of the formation of metal boride at the interface. This provides a new avenue toward the development of a composite materials containing B4C.
8:30 AM
Microstructure Analysis and Modeling of the Effective Properties of Damaged Fe-TiB2 Metal Matrix Composites: Khaoula Dorhmi1; Katell Derrien1; Zehoua Hadjem-Hamouche1; Leo Morin1; Frederic Bonnet1; Jean-Pierre Chevalier1; 1PIMM-ENSAM
Fe-TiB2 metal-matrix composites have been designed and produced by ArcelorMittal, using in situ precipitation of TiB2 particles during eutectic solidification which leads to very clean and particularly strong matrix/reinforcement interfaces. Significant fractions of ceramic reinforcement (10-25% by volume) can be reached through the control of the nominal composition of the material while the size of the reinforcement can be optimized through the local solidification rate. This process leads to an increase of specific stiffness by at least 20%. Initial microstructures of Fe-TiB2 composites are investigated experimentally by SEM and in situ tensile test are carried out to define and quantify damage mechanisms. Random and representative microstructures of the hot and cold rolled composites are generated by the RSA method. The effective elastic properties of these composites are then determined by numerical homogenization based on the FFT method. Numerical results are successfully compared to experimental ones.
8:55 AM
Effects of Interface Characteristics on High Volume Fraction Al/SiCp Composites under Compressive Stress: Taegyu Lee1; Donghyun Lee2; Hobyung Chae3; Soo Yeol Lee3; Ho Jin Ryu1; 1Korea Advanced Institute of Science and Technology; 2Korea Institute of Materials Science; 3Chungnam National University
Enhanced mechanical properties of high-volume-fraction (~55vol%) SiCp/Al composites were acquired by matrix-reinforcement interface modification. The interface modification was performed to increase mechanical properties of high-volume-fraction SiCp/Al composites by forming an additional layer on SiC particles by oxidation. The surface of two types of SiC reinforcements (coarse (30 μm) and fine (10 μm)) was oxidized and a 200 nm thick SiO2 layer was formed on the SiC surface. The interface modified SiCp/Al composites were fabricated by liquid pressing and the compression test was conducted under the in-situ neutron diffraction measurement system. The additional layer was transmuted to MgAl2O4 after the fabrication and it prevented a formation of brittle Al4C3. The change of interface characteristics increased the strength and the fracture strain for the coarse and fine SiCp composites, respectively. We found that the interface modification enhances the mechanical properties and the mechanism of the properties enhancement varies with the reinforcement size.