The AlFeNiTiZn high entropy alloy with a mean crystallite size of 35–45 nm was synthesized within a two-stage process. Firstly, as a powder form using a planetary ball mill in an argon atmosphere and after that compressed the powder samples and sintered them in tube furnace as bulk samples. The X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques were used to examine the structural and morphological changes during the process. The two-phase solid solution (FCC + BCC) was formed after mechanical alloying. In addition to FCC + BCC, gahnite (ZnAl2O4) was synthesized after sintering. A differential scanning calorimetry analysis has also confirmed that recrystallization took place at 311 °C. Nucleation and growth were adequate explanations for the mechanochemical synthesis of the AlFeNiTiZn high entropy alloy based on Johnson-Mehl-Avrami model. An interface-controlled growth was the conversion mechanism based upon the Avrami exponent. According to a vibrating sample magnetometer, both as-milled and as-sintered alloys have semi-hard magnetic properties with 37.42 and 25.43 emu/g saturation magnetization, respectively. In sintered HEA, the microhardness was measured to be about 724 ± 15 HV.