Effect of ZrB<sub>2</sub> Nanoparticle Addition: Nano-LPSO-Grain Structured Ultra-High Strength Mg-RE Alloy

Abstract

Currently, long period stacking/ordered phases (LPSO phases) are known to reinforceMg97Y2Zn1 type Mg-RE alloys. The LPSO phases are composed of a solid solution of Y and Znatoms placed orderly in long periods along the Mg basal plane. Also, an efficient way to strengthena polycrystalline material is to reduce its grain size. This increases the density of grain boundarieswhich impede the flow of dislocations. In many of the LPSO forming solidification processed Mg-RE alloys, the common practice is to solutionize the ingot, quench in warm water, hot extrude andthermally age. While this practice is suitable for obtaining high strength Mg-RE alloys, itconveniently employs the common idea in conventional metallurgy of fine intermetallicstrengthening while refining the grain size to within the micron regime. In this work, an alternativemethod involving boride nanoparticle addition to obtain a selected solidification processed ultrahighstrength (tensile yield strength > 400 MPa) Mg-RE alloy is discussed. Here, LPSO phaserather than fine intermetallic formation while retaining grain size under the micron regime ishighlighted.