The effects of Ca and Mn on the microstructure,texture and mechanical properties of Mg-4 Zn alloy

The microstructural evolution,texture and mechanical properties of nine Mg-4Zn-xCa-yMn alloys(x=0.3,0.6,1.0;y=0.2,0.3,0.7 wt.%)were investigated systematically.Alloying with Ca and Mn refined the grains of the extruded sheets and increased the unDRX fraction.Mn could be the heterogeneous nucleation site of Ca2Mg6Zn3 phase because of a good atom matching at the orientation relationship of(211)_(Mn)//(1211)_(Ca2Mg6Zn3),(251)_(Mn)//〈1103〉_(Ca2Mg6Zn3).The traditional texture weakening effect of Ca was strongly decreased for the simultaneously addition of Mn.With increasing Ca and Mn concentration,the strength increased and ductility decreased.Mg-4Zn-0.6Ca-0.7Mn exhibited a good combination of ultimate tensile strength(320 MPa),yield strength(286 MPa)and elongation(16%).A model of strengthening indicated that grain boundary strengthening and precipitate strengthening made a large contribution to the strength of Mg-4Zn-0.6Ca-0.7Mn.In addition,the dynamic recrystallization,texture modification and the strengthening effect from different parts also have been analyzed in detail.

Correlating oriented grain number density of recrystallisation in particle-containing aluminium alloys

The recrystallized grain structure of Al-（Mn）-Fe-Si alloys after isothermal annealing was studied by electron backscatter diffraction（EBSD） technique. Statistical correlation suggests that the frequency of forming P-oriented（{011}？566？） grains at a particle larger than the critical diameter（about 1.1 μm） is about 2% when the effect of fine dispersoids and concurrent precipitation is negligible. The overall grain number density is correlated linearly with the number densities of P and Cube（{001}？100？） grains. The grain number densities of typical orientations（P, ND-rotated cube {001}？310？ and Cube） and the overall recrystallized grains increase as rolling strain increases, following a similar exponential law.

Effect of Bimodal Quasicrystal Phase on the Dynamic Recrystallization of Mg–Zn–Gd Alloy during High-Pressure Torsion

The Mg–Zn–Gd alloy with quasicrystal icosahedral phase was processed by high-pressure torsion (HPT). The effect of bimodal I-phase on the dynamic recrystallization was analyzed by transmission electron microscopy. The results showed that the block I-phase can stimulate obvious particle-stimulated nucleation and dynamic recrystallization (DRX) grains were preferentially formed after HPT for 5 turns, while the granular I-phase only promoted the generation of sub-grains. The orientation relationship was determined as twofold//[1210] and fivefold//(0002)_(Mg). Moreover, after HPT for 9 turns, the DRX grains induced by block I-phase appeared to grow up and coarsened. Compared with block I-phase, the grains induced by granular I-phase presented much smaller size and distributed more homogeneous due to the strong pinning effect.

High-temperature deformation behaviors of Ti-2Al-9.2Mo-2Fe alloy with boron

Hot deformation behaviors of Ti-2Al-9.2Mo-2Fe alloy with boron were investigated in a hot compression test at temperatures ranging from 850 to 1000℃and strain rates ranging from 0.01 to 10.00 s^(-1).With strain rate decreasing and deformation temperature increasing,dynamic recrystallization(DRX)was promoted in both alloys.The nucleation mechanism of DRX involved grain boundary bulging and subgrain rotation.In case of deformation at low temperatures and high strain rates,the boronfree alloy only showed dynamic recovery(DRV)phenomenon.However,due to the particle-stimulated nucleation mechanism of recrystallization by TiB particles,the boron-containing alloy shows DRX at that condition.These DRX grain nuclei are formed by lattice rotation and subgrain growth from deformation zone in the initial grains,which are close to those of TiB particle.Moreover,the flow stress of the boron-containing alloy is lower than that of the boron-free alloy due to the grain refinement during hot deformation process.