Abstract: As-cast ZrBN alloys (BN=0.5wt%, 0.7wt%, 1.0wt%, 1.5wt%, 2.0wt%) were prepared via non-consumable arc melting furnace under Ar atmosphere. The effect of the BN content on the phase structure, microstructure and mechanical properties of the ZrBN alloys were examined by means of optical microscopy (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), micro-hardness tester and mechanical properties testing system.The results show that the diffraction peaks of the intermetallic ZrB ₂ phase are presented after BN addition, and their intensities increase with the BN content increasing. With the addition of BN, the grain size of the alloys is obviously refined and evenly distributed,while the size of the rod-like ZrB ₂ phase increases rapidly when the BN content reaches 1.5wt%. When the BN content is 0.5wt%,the alloy possesses excellent comprehensive mechanical properties,with the compressive strength, yield strength and compressive plasticity being 1311 MPa, 928 MPa and 16.71%, respectively, and the compressive fracture morphology presents the ductile fracture mode. Whereas, when the BN content is increased further, the ductility of the alloys dramatically declines, and the compressive fracture changes gradually to the brittle one.

Key words: Zr alloy, microstructure, mechanical properties, phase structure