Microstructural and mechanical evaluation of Al–TiB2 nanostructured composite fabricated by mechanical alloying

Production of bulk Al–TiB2 nanocomposite from mechanically alloyed powder was studied. Al–20 wt.% TiB2 metal matrix nanocomposite powder was obtained by mechanical alloying (MA) of pure Ti, B and Al powder mixture. A double step process was used to prevent the formation of undesirable phases like Al3Ti intermetallic compound, which has been described in our previous papers. The resultant powder was consolidated by spark plasma sintering (SPS) followed up by hot extrusion. The structural characteristics of powder particles and sintered samples were studied by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Hardness measurements were conducted on the cross section of powder particles and sintered sample and the tensile behavior of extruded samples was evaluated. The results showed that the prepared Al–20 wt.% TiB2 nanocomposite has good thermal stability against grain growth and particle coarsening. Extruded Al–20 wt.% TiB2 showed a hardness value of 180 VHN and yield and tensile strength of 480 and 540 MPa, respectively, which are much higher than those reported for similar composites made by other processes.

► Production of bulk Al–TiB2 nanocomposite from mechanically alloyed powder was studied. ► Al–20 wt.% TiB2 metal matrix nanocomposite powder was obtained by double step mechanical alloying (MA) of elemental Ti, B and Al powder mixture. ► The resultant powder was consolidated by spark plasma sintering (SPS) followed up by hot extrusion. ► Al–20 wt.% TiB2 nanocomposite presented a good thermal stability against grain growth and particle coarsening. ► Consolidated material showed a hardness value of 180 VHN and yield and tensile strength of 480 and 540 MPa, respectively, which are much higher than those reported for similar composites made by other processes.