Yttrium Addition Co‐Enhances the Plasticity and Corrosion Resistance of TiB ₂ ‐Refined Al‐Mg‐Zn Alloys

To address the degradation of corrosion resistance induced by Al‐5Ti‐B grain refiner during the strengthening of Al‐Mg‐Zn alloys, this study innovatively employed a rare earth element yttrium (Y) alloying strategy to achieve synergistic enhancement of mechanical strength and corrosion resistance. Microstructure analysis revealed that the introduction of Y further refined the grain structure, resulting in a 27.7% decrease in average grain size. The synergistic addition of Y and Al‐5Ti‐B achieved an optimal balance between strength and ductility, and the ultimate tensile strength rose to 381 ± 11 MPa while elongation remained at 17.2% ± 1.3%. Electrochemical measurements and immersion tests confirmed that the preferential dissolution of Al 3 Y intermetallic particles promoted the formation of a dense corrosion product layer composed primarily of Al 2 O 3 and Y 2 O 3 . The layer suppressed pit propagation and markedly improved corrosion resistance, as evidenced by a reduced corrosion current to 0.17 μA cm −2 , and a shift in corrosion potential to −0.90 V SCE . Scanning Kelvin probe force microscopy measurements found that Y doping effectively reduced the potential difference between TiB 2 particles and the matrix from 245 to 190 mV, thereby mitigating the galvanic corrosion effects.