Thermal expansion behavior of Al hybrid composite reinforced with aluminum borate whisker and magnetic ceramic particle

Magnetic ceramic particles (NiFe₂O₄) and aluminum borate whiskers reinforced aluminum matrix composite was fabricated by squeeze casting technique, which had lower coefficients of thermal expansion (CTEs). The components and microstructure were characterized by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The results showed that the CTE of the composite was lower than that of the composite only reinforced by aluminum borate whisker, and with increasing the number of thermal cycling, the CTE of the composite became low. The results indicated that the lower CTEs of composite resulted from ferromagnetic-paramagnetic transformation of the magnetic ceramic particles.