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The formation of the AIMI MgB2 wire is based on the infiltration of Mg into B powder layer at 650 °C to 675 °C. This study focused on the effect of oxide dopants on the MgB2 phase formation during the diffusion of Mg into the B powder layer. In Dy2O3 doped MgB2 AIMI wires, Dy2O3 reacted with melting Mg to form DyB4 and MgO during heat treatment. The unreacted Dy2O3, DyB4 and MgO have the potential to work as flux pinning centers or to refine MgB2 grain size in the AIMI wires. X-ray powder diffraction (XRD) was used to analyze the formation of the major impurity phases in the MgB2 wires. The plot of pinning force versus magnetic field was obtained to indicate the flux pinning mechanisms of the Dy2O3 doped MgB2 AIMI wires. On the other hand, the influence of Dy2O3 on the Mg infiltration depth was studied. The MgB2 area fraction of Dy2O3 doped MgB2 AIMI wires were compared with that of undoped MgB2 AIMI wires under same heat treatment condition. The transverse cross sectional areas of the MgB2 wires were observed by scanning electron microscope (SEM).