Microstructure and Mechanical Properties of Ni-20Cr-Eu₂O₃ Composites Prepared by Vacuum Hot Pressing

Ni-20Cr-Eu₂O₃ composites were designed as new control rod materials and were synthesized from Ni, Cr, and Eu₂O₃ mixture powders via ball milling and vacuum hot pressing. During ball milling, Eu₂O₃ was fined, nano-crystallized, amorphized, and then dissolved into matrix. The effect of Eu₂O₃ content on the microstructure and mechanics was researched, and the corresponding mechanism was discussed. The relative densities, grain sizes, and microhardness increased when Eu₂O₃ content increased. According to the TEM observations, Eu₂O₃ particles showed a semi-coherent relationship with the matrix. The results of mechanical property testing showed that the ultimate tensile strength, yield strength, and elongation decreased with the Eu₂O₃ content increased. The maximum ultimate tensile strength, yield strength, and elongation were 741 MPa, 662 MPa, and 4%, respectively, with a 5 wt.% Eu₂O₃ addition. The experimental strengths were well matched with the theoretical values calculated by the strengthening mechanisms indicating that this method was highly effective for predicting the mechanical properties of Ni-20Cr-Eu₂O₃ composites.