HALL-PETCH RELATIONSHIP WITH ULTRAFINE GRAINS IN Zn-22%Al-4%Ag ALLOY IN SEVERE PLASTIC DEFORMATION CONDITIONS

Abstract

The comparative study of compression and lamination of three groups of specimens in different microstructural conditions of the ZnAlAg alloy and recognized for its superplastic behavior. They are compressed at staggered loads to homogenize and refine the grain size. The X-ray diffraction identified the crystalline phases a, ?, and the intermetallic e. The X-ray diffraction (XRD) shows a position and evolution according to the applied load. The microhardness test carries out in the plastic and packing zone with a diamond indenter and a 50gf load under the ASTM E384 standard. The evolution in the diffraction peaks, microhardness, and applied load found a relationship statistically. The alloy Zn - 22% Al - 4% Ag can be heat treated before a deformation process, allowing more plasticity due to the refinement grain, the distribution of the intermetallic e, and the absence of work hardening allow a softening or a negative slope of the Hall-Petch model. Key Words: Hall-Petch, ZnAlAg alloy, DRX, Superplasticity