Microstructure and corrosion behavior of as-homogenized and as-extruded Mg-xLi-3Al-2Zn-0.5Y alloys(x=4,8,12)

The microstructure and corrosion behavior of the as-homogenized and as-extruded Mg-xLi-3Al-2Zn-0.5Y alloys(x=4,8,12,wt.%)were studied.The results show that as the Li content increases from 4%to 12%,the matrix transfers from singleα-Mg phase,(α-Mg+β-Li)dual phase to singleβ-Li phase.A mixed corrosion feature of intergranular corrosion and pitting corrosion occurs in the Mg-4Li-3Al-2Zn-0.5Y and Mg-12Li-3Al-2Zn-0.5Y alloys.The former is related to the precipitated AlLi phase along the grain boundaries,and the latter is related to the high potential difference between the second phase and the matrix.The corrosion resistance of the as-extruded alloys is better than that of the as-homogenized alloys.The superior corrosion resistance of the as-extruded Mg-8Li-3Al-2Zn-0.5Y alloy with the lowest corrosion rate(P_(W)=(0.63±0.26)mm/a)is attributed to the more uniform distribution of second phases,the protectiveα-Mg phase via sacrificing theβ-Li phase and the relatively integrated oxide film.

Superplasticity of a Ti-24Al-14Nb-3V-0.5Mo Intermetallic Alloy

Superplastic properties and microstructural evolution of a Ti-24Al-14Nb-3V-0.5Mo (at. pct) intermetallic alloy were studied. Optimum superplastic properties were obtained for temperatures in the interval 960℃≤5 T≤5980℃. The apparent activation energy in the superplastic regime was determined and the deformation mechanism was also discussed. Based on the studies, a curve panel with three sheets sandwich structure was fabricated successfully. The microstructures corresponding to different strain in the part were also studied.

Anisotropic compressive deformation behavior of hot-rolled Mg-3Al-0.5Ce alloy

This work investigates the anisotropic compressive deformation of hot-rolled Mg-3Al-0.5Ce alloy and correlates it with microstructure and texture.Hot-rolled alloy had elongated and equiaxed grains with long-aligned Al11Ce3precipitates within the grain boundaries along rolling direction (RD) and basal texture along normal direction (ND).Analytical and crystal plasticity-based viscoplastic self-consistent predominant twin reorientation (VPSC-PTR) approaches were employed to simulate the flow curve and texture evolution for deeper insight into the deformation behavior.For compression direction (CD)∥to RD and transverse direction (TD),the basal texture was~⊥to CD which favored{10.12}{10.11}extension twins (ET).The ETs nucleate,broaden and engulf the parent matrices with strain,rotating the lattice by~86.4?about{2110}axes to a geometrically hard orientation with c-axis~∥to CD,leading to sigmoidal flow and increasing stage-II strain hardening rate (SHR).However,Al11Ce3weakened the basal texture intensity,reducing the stage-II strain hardening compared to the single-phase Mg alloy investigated earlier.The presence of Al11Ce3intermetallics delayed the ET nucleation event,which initiates atε~0.018.The ET fraction evolves to~0.85,lower than in the previous works on single phase Mg alloy.A reduction in the+ve SHR slope could be observed from ε=0.03 to 0.06,indicating increased slip activities in this portion of stage-II.Beyond ε=0.1,decreasing stage-III SHR was observed due to basal?a?,and pyr?c+a?-I and II slip activities in the ET orientation.The difference in the compressive behavior along RD and TD could not be observed due to Al11Ce3precipitate’s morphology with elongation along RD.For CD∥to ND,the compressive flow behavior was parabolic with decreasing SHR due to slip-based deformation.ET didn’t form,and the texture change was negligible,with initial and final textures having basal texture~∥to CD,the geometrically hard orientation.