Effect of Ca Addition on the Intensity of the Rare Earth Texture Component in Extruded Magnesium Alloys

Wang, Tong; Jiang, Lan; Mishra, Raja K.; Jonas, John J.

doi:10.1007/s11661-014-2371-5

Cited by 45 publications

(16 citation statements)

References 23 publications

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“…Recently, it has been pointed out that Ca seems to be one feasible candidate to replace expensive RE elements, considering its large atomic radius equivalent to RE elements and relatively high solubility in Mg [18]. As expected, typical RE texture was obtained in binary Mg-Ca alloys after hot extrusion [19,20]. A similar texture modification effect of Ca addition has also been observed in AZ31 [21], Mg-Mn-Ca [19] and Mg-Zn-Ca [22][23][24] alloys.…”

supporting

confidence: 66%

“…8) orientation parallel to the ED, which is commonly observed in commercial Mg alloys after hot extrusion [10,43]. Upon the basis of the previous studies on the effect of Ca on the extrusion texture [18][19][20][21][22][23][24], as stated earlier, it is suggested that Ca addition might have a strong implication for the formation of RE texture in dilute…”

Section: Resultsmentioning

confidence: 73%

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High-speed extrusion of dilute Mg-Zn-Ca-Mn alloys and its effect on microstructure, texture and mechanical properties

Jiang

Nakata

et al. 2016

Materials Science and Engineering: A

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Three dilute Mg-Zn-Ca-Mn alloys were successfully extruded at 24 m/min and the alloy with lowest Zn content (0.21 wt.%) can even be extruded at 60 m/min without any surface defects, which was ascribed to the thermally stable Mg 2 Ca phase and high solidus temperature (620 o C). The alloys extruded at die-exit speed  6 m/min showed a fully dynamically recrystallized (DRXed) microstructure and weak rare earth (RE) texture at the position between [2 4] and [2 2] parallel to the extrusion direction. Besides, fine Mg 2 Ca and -Mn particles dynamically precipitated during extrusion, acting as effective pinning obstacles against the DRXed grain growth via Zener drag effect. Due to the deformation temperature rise with increasing extrusion speeds, the grain size increased gradually, which can be understood from the relationship between DRXed grain size and Zener-Hollomon parameter. The RE texture contributed to high uniform elongation of 23%, but the increased grain size ( 30 m) deteriorated post-uniform elongation due to the prevalence of {10 1} contraction and {10 1}-{10 2} double twins during post-uniform deformation.

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supporting

confidence: 66%

Section: Resultsmentioning

confidence: 73%

High-speed extrusion of dilute Mg-Zn-Ca-Mn alloys and its effect on microstructure, texture and mechanical properties

Jiang

Nakata

et al. 2016

Materials Science and Engineering: A

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“…Therefore, significant segregation at GBs or dislocations can be expected. A so-called RE texture was obtained in binary Mg-Ca alloy (Ca = 0.5 and 1.0 wt.%) after extrusion at 200 and 250°C, which was explained by the dynamic strain aging resulting from dislocation pinning by Ca [63]. A similar effect of Ca addition has also been seen in other alloys, like Mg-Zn-Ca alloy [64][65][66], Mg-AlCa alloy [64,67] and AZ31 [68].…”

Section: Summary and Future Perspectivesmentioning

confidence: 55%

Role of RE in the deformation and recrystallization of Mg alloy and a new alloy design concept for Mg–RE alloys

et al. 2015

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“…Likewise, it has been argued [89] that when Gd is partially replaced by Y in the Mg-GdZn-Zr alloy the precipitates become smaller due to the lower diffusion rate of the (larger than Gd) Y atoms. Similar arguments have been applied to Ca [100]. However, no direct evidence of size related effects on the diffusivity of substitutional solutes in Mg alloys, or any other alloy system for that matter, seems to be available in the literature.…”

Section: Atomic Size Controlled Diffusivitymentioning

confidence: 78%

Thermodynamics-based design of creep resistant Mg solid solutions using the Miedema scheme

Abaspour¹

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Most current creep resistant alloy design methods for Mg alloys aim at incremental strengthening of existing alloys such as AZ91 thorough addition of ternary and quaternary elements, or alternatively through RE's additions. The most remarkable improvements has been through either Mg-Y or recently developed Mg-Gd-Y-Zr and Mg-Y-Nd-Zr alloys, although still below the strength of MgTh alloys, which are being phase out due to Th's radioactivity.Many micromechanisms proposed to account for the observed improvements in either hardness or creep strength of Mg alloys including solid solution and/or precipitation hardening, dynamic precipitation, solute dragging/solute clustering and more importantly atomic size controlled diffusivity more often than not are little more than ad-hoc, after-the-fact explanations, valid at best for the particular system under consideration. Hence, extrapolation to other alloy-systems is either not possible or contradictory. In practice, a feasible path for systematic, either precipitationhardened or creep-resistant Mg alloys, selection and design is still lacking.The aim of the present work was to use atomic level thermodynamical arguments that suggest that extending the athermal regime through short range order (SRO) is a most feasible path to increasing the creep strength of Mg alloys. Potential solutes were sorted out and ranked based on their tendency to developing SRO using the Miedema's phenomenological scheme. The predictions were corroborated by experiments involving dilute binary alloys as well as through a collection of data from the literature.Monotonic compression and stress relaxation tests were carried out on specimens of 6 cast binary alloys with (at.%) 2.5 Al, 0.6 Sn, 2.2 Zn, 0.8 Gd, 1.3 Y and 0.9 Nd, and of a similarly cast AZ91D alloy for reference. The solute concentration in the binary alloys was kept deliberately low to limit precipitation hardening effects during the testing. Compression testing was carried out at 298K (25°C), 373K (100°C) and 453K (180°C) The relative tendency or lack of it, of most solutes to develop SRO rationalizes a number of observations in current multicomponent Mg alloys while it disputes the viability of several other micromechanisms often considered.The feasibility of strengthening HPDC Mg alloys through a combination of percolating eutectics and residual solute in solution, or, more generally, age hardenable alloys through either homogeneously nucleated, coherent with the Mg matrix, precipitates, or via internally ordered precipitates mimicking Mg-Th alloy system, is also considered by making parallels with either the Al-Zn or the Al-Cu alloy systems. Examples of these approaches were discussed using data from the literature, such as experiments on alloys combining Mn and Sc to introduce order in the soft Mn precipitates, or the use of Na to provide finely dispersed, homogeneously nucleated clusters with the aim of refining the subsequent precipitation in alloys such as Mg-Sn. III Declaration by authorThis thesis is composed of my or...

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Effect of Ca Addition on the Intensity of the Rare Earth Texture Component in Extruded Magnesium Alloys

Cited by 45 publications

References 23 publications

High-speed extrusion of dilute Mg-Zn-Ca-Mn alloys and its effect on microstructure, texture and mechanical properties

High-speed extrusion of dilute Mg-Zn-Ca-Mn alloys and its effect on microstructure, texture and mechanical properties

Role of RE in the deformation and recrystallization of Mg alloy and a new alloy design concept for Mg–RE alloys

Thermodynamics-based design of creep resistant Mg solid solutions using the Miedema scheme

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