Processing and characterization of Cu-Al2O3 and Al-Al2O3 composites: an evaluation for micro- and nano- particulate reinforcements

Composites are formed by the physical association of matrix and reinforcement and possess intermediate properties of the components’ it is constituted of. Metal matrix composites (MMCs) reinforced with ceramic particles furnishes ductility along with strength and has been into practice since decades. The applications cater the aerospace and automobile industries such as turbine rotatory machinery components, rocket turbine housing, cryostat, cryo-pump impeller and cryo-pump inducer. Powder metallurgy has been a conventional still inevitable technique to serve the automotive and aerospace industries with components of utmost importance. The powder metallurgy process consists of several steps which are crucial to the end products’ properties. This work aims at investigating some of the steps to assess the microstructure and properties of copper and aluminium based composites varying the reinforcement particle size and volume fraction. Structural integrity is a vital factor of a composite which accounts for the physical intimate bonding of matrix and reinforcement. This factor varies with the fabrication parameters and techniques which are also fundamental for effective stress transmissibility from matrix to reinforcement. Structural integrity of a composite material also fluctuates within the service life of the material, for eg. during harsh and hostile environment thermal exposures

Compressive creep of SiC whisker/Ti3SiC2 composites at high temperature in air

The compressive creep of a SiC whisker (SiCw) reinforced Ti3SiC2 MAX phase‐based ceramic matrix composites (CMCs) was studied in the temperature range 1100‐1300°C in air for a stress range 20‐120 MPa. Ti3SiC2 containing 0, 10, and 20 vol% of SiCw was sintered by spark plasma sintering (SPS) for subsequent creep tests. The creep rate of Ti3SiC2 decreased by around two orders of magnitude with every additional 10 vol% of SiCw. The main creep mechanisms of monolithic Ti3SiC2 and the 10% CMCs appeared to be the same, whereas for the 20% material, a different mechanism is indicated by changes in stress exponents. The creep rates of 20% composites tend to converge to that of 10% at higher stress. Viscoplastic and viscoelastic creep is believed to be the deformation mechanism for the CMCs, whereas monolithic Ti3SiC2 might have undergone only dislocation‐based deformation. The rate controlling creep is believed to be dislocation based for all the materials which is also supported by similar activation energies in the range 650‐700 kJ/mol