Microstructure and mechanical properties of Fe matrix composites reinforced by nickel–chromium double-layer coated ZTAP ceramics

The preparation, microstructure and mechanical properties of ZTA particles reinforced Fe matrix composites (ZTA P /Fe composites) were systematically investigated. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were used to analyze the microstructure and phase constituents, the hardness ( H) , Young's modulus ( E ) and plasticity factor ( δ A ) were determined as well. The nickel-chromium double-layer coated ZTA P of core-shell structure was prepared by electroless plating and multi-arc ion plating technologies. The modified ZTA P is consisted of the α -Al 2 O 3 , t -ZrO 2 , α -Cr and γ -Ni phases. In addition, the compressive strength of ceramic preforms is high due to a compact sintering neck formed among ZTA P during high temperature sintering . The preferred sintering process for ZTA ceramic preforms is determined as 1350 °C + 1 h, in this case the preforms show the remarkable porosity and highest compressive strength which are 27.8% and 35.0 MPa, respectively. The interfacial metallurgical chemical reactions occurred during infiltration casting process, which ensure the excellent metallurgical interfacial bonding of the ZTA P /Fe composites. The interface contains double transition layers, which refer to silicate and CrFe phases, respectively. The H , E and δ A of interfacial double transition layers were measured by the nano-indentation method, the values of which are situated between the ZTA P and iron matrix.