Unexpectedly high precipitation hardening induced by supersaturated solute and strong texture in a Mg-13Gd binary alloy after forging

Obtaining exceptionally high strength in large-scale Mg alloys using conventional free-forging process is an enormous challenge since high-temperature forging is difficult to produce ultrafine grains. In this work, we achieved ultrahigh strength, such as yield strength of 458 MPa and ultimate tensile strength of 493 MPa, in coarse-grained Mg-13Gd forged alloys by maximizing precipitation hardening effect, which exceeds that of conventionally free-forged Mg alloys documented previously. High-temperature forging, while does not refine the grain below the micron level, favors the formation of strong basal texture and suppresses dynamic precipitation to enable supersaturated Gd atoms in the matrix, which provides a favorable precondition for the unexpectedly high precipitation hardening in the following ageing. As a result, further ageing treatment produces a surprisingly high increment of over 170 MPa in yield strength, breaking through the previous highest record in precipitation-hardened Mg alloys. Thus, we creatively proposed a new strategy for fabricating high-strength forged Mg alloys via constructing texture hardening and maximizing precipitation hardening. These results provide important implications for fabricating high-strength Mg forgings.