Alloy Design and Processing Design of Magnesium Alloys Using 2nd Phases

Abstract

Two phases dominate the performance of commercial Mg alloys: (1) b Mg 17 Al 12 and (2) porosity. Alloy design and process design to optimize the morphology of the first and to minimize the second are discussed. Second phase b can be designed to improve tensile strength, fatigue strength, toughness, texture, formability and corrosion resistance of Mg alloys. Processing is applied to refine the grain size, to array this phase in micron sizes at grain boundaries, and to further precipitate this phase in nanometer arrays within the grains. Therein, the 2nd phase b plays the following roles: (1) retarding grain growth, (2) randomizing texture, (3) Hall-Petch hardening, (4) Orowan hardening, and (5) moderating corrosion. Porosity is a detrimental 2nd phase common to cast Mg alloys in the form of gas or voids; its control being essential to engineering applications. Porosity can be diminished by sub-liquidus molding with high-velocity/high-pressure injection and then eliminated by subsequent hot deformation.

Study of mechanical characteristics and microstructure on ZM21 alloy with Tricalcium Phosphate using Friction stir processing

“…6(b)). Because of the high strain rate associated with the process of dynamic recrystallization (21,22) as well as the blockage of dislocation movement with high density [29], FSP was found to improve grain re nement (23) signi cantly. Grain development in ZM21-ß-TCP composites was signi cantly reduced because of the pinning factor of the distributed ß-TCP aggregates.…”

“…The contrary is true for Mg alloys, wherein the strength is diminished by a decrease in the amount of secondary phase. (29) Changing metal matrix size and form at grain boundaries degrades FSP ZM21 alloy's bulk mechanical behaviour. Supersaturated grains enhance FSP ZM21's tensile strength.…”

Análisis térmico y comportamiento de desgaste de aleaciones Mg-4Zn-(x)Zr fundidos en molde de cáscara y molde de grafito

“…Zinc is the second element that is used to alloy that affects the strength, castability, eutectic phase of grain boundary, corrosion resistance, and precipitation hardenability of some magnesium alloys (El Mahallawy et al, 2017;Decker et al, 2019). Zirconium is used in Mg alloys for grain refinement; it is currently the well-known element that has potent grain refining effects on the Mg-Zn alloys (Wang et al, 2014;Karakulak, 2019).…”