Microstructural evolution of Mg–Al–Ca–Sr alloy during creep

Sato, Takanori; Kral, Milo V.

doi:10.1016/j.msea.2008.08.006

Cited by 26 publications

(6 citation statements)

References 23 publications

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“…From this viewpoint, commercial Mg alloys like AE42 and MRI230D have been developed [2,3], in which creep strength is improved by the addition of rare-earth and alkaline-earth elements like Ca and Sr, respectively. In Mg-Al and Mg-Al-Zn alloys, the room temperature and elevated temperature strength are improved by the addition of Ca and Sr [4][5][6] through microstructural refinement and texture strengthening [7,8]. However, the quest for finding better creep-resistant Mg alloys continues, and a new alloy class is based on an Mg-Al-Ba-Ca (ABaX) system [9][10][11], where the strength is increased with increasingly higher alloying content.…”

Section: Introductionmentioning

confidence: 99%

Connected Process Design for Hot Working of a Creep-Resistant Mg–4Al–2Ba–2Ca Alloy (ABaX422)

Rao

Dharmendra

Suresh

et al. 2018

Metals

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With a view to design connected processing steps for the manufacturing of components, the hot working behavior of the ABaX422 alloy has been characterized for the as-cast and extruded conditions. In the as-cast condition, the alloy has a limited workability, due to the presence of a large volume of intermetallic phases at the grain boundaries, and is not suitable to process at high speeds. A connected processing step has been designed on the basis of the results of the processing map for the as-cast alloy, and this step involves the extrusion of the cast billet to obtain a 12 mm diameter rod product at a billet temperature of 390 • C and at a ram speed of 1 mm s −1. The microstructure of the extruded rod has a finer grain size, with redistributed fine particles of the intermetallic phases. The processing map of the extruded rod exhibited two new domains, and the one in the temperature range 360-420 • C and strain rate range 0.2-10 s −1 is useful for manufacturing at high speeds, while the lower temperature develops a finer grain size in the product to improve the room temperature strength and ductility. The area of the flow instability is also reduced by the extrusion step, widening the workability window.

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Section: Introductionmentioning

confidence: 99%

Connected Process Design for Hot Working of a Creep-Resistant Mg–4Al–2Ba–2Ca Alloy (ABaX422)

Rao

Dharmendra

Suresh

et al. 2018

Metals

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“…Normally, the creep behaviors involve the time dependent plastic deformation of alloys at constant or varying stresses, leading to the perpetual deformation of components . Furthermore, the creep deformation becomes apparent with the increase of temperature and stress . The fracture caused by creep deformation is closely related to the nucleation and growth of voids or cracks in the matrix .…”

Section: Introductionmentioning

confidence: 99%

Effects of Initial δ Phase on Creep Behaviors and Fracture Characteristics of a Nickel‐Based Superalloy

et al. 2017

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Uniaxial creep tensile experiments are performed to study the influences of initial δ phase (Ni 3 Nb) on the creep features and fracture behaviors of a nickel-based superalloy. Experimental results show that the creep features and fracture behaviors of the researched superalloy are closely relevant to the volume fraction of initial δ phase. The minimum creep rate increases with the increased volume fraction of initial δ phase. The appropriate volume fraction of initial δ phase can improve the creep resistance and plasticity. So, the rupture time and the elongation to fracture initially increase, when the volume fraction of initial δ phase is relatively low, and then decrease with the increase of volume fraction of initial δ phase. Additionally, with the increased initial δ phase, the failure mode changes from a typical intergranular fracture to the mixed fracture pattern of ductile intergranular and cleavage fracture.

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“…A second APT measurement on the same alloy showed similar concentrations of the elements in the IP. Works from the literature report ternary MgAlSrCa phase compositions in the microstructure of Mg-Al-Ca-Sr alloys; see for example [32][33][34][35].…”

Section: Apt Measurementsmentioning

confidence: 99%

“…X-ray diffraction measurements from Aghion et al [31] revealed only the presence of α-Mg and Al 2 Ca in the case of the alloy MRI 230D. Other groups report ternary MgAlSrCa phase compositions in Mg-Al-Ca-Sr alloys; see for example [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Understanding the High Creep Resistance of MRI 230D Magnesium Alloy through Nanoindentation and Atom Probe Tomography

Matschkal-Amberger¹,

Tuengerthal²,

Lamm³

et al. 2021

Metals

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Due to their low density, magnesium alloys are very appealing for light-weight constructions. However, the use of the most common magnesium alloy, AZ91 (Mg 9 wt.% Al, 1 wt.% Zn), is limited to temperatures below 150 °C due to creep failure. Several alloys with an improved creep resistance have been developed in the past, for example the alloy MRI 230D or Ca-alloyed AZ91 variants. However, there is an ongoing discussion in the literature regarding the mechanisms of the improved creep resistance. One factor claimed to be responsible for the improved creep resistance is the intermetallic phases which form during casting. Another possible explanation is an increased creep resistance due to the formation of precipitates. To gain more insight into the improved creep resistance of MRI 230D, nanoindentation measurements have been performed on the different phases of as-cast, creep-deformed and heat-treated samples of MRI 230D and Ca-alloyed AZ91 variants. These nanoindentation measurements clearly show that the intermetallic phase (IP) of the alloy MRI 230D does not lose strength during creep deformation in contrast to the Ca-alloyed AZ91 variants. High-temperature nanoindentation measurements performed at 200 °C clearly show that the intermetallic phases of the MRI 230D alloy maintain their strength. This is in clear contrast to the Ca-alloyed AZ91 variants, where the IP is significantly softer at 200 °C than at room temperature. Atom probe measurements have been used to gain insight into the differences in terms of chemical composition between the IPs of MRI 230D and the Ca-alloyed AZ91 variants in order to understand the dissimilar behaviour in terms of strength loss with increasing temperature.

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Microstructural evolution of Mg–Al–Ca–Sr alloy during creep

Cited by 26 publications

References 23 publications

Connected Process Design for Hot Working of a Creep-Resistant Mg–4Al–2Ba–2Ca Alloy (ABaX422)

Connected Process Design for Hot Working of a Creep-Resistant Mg–4Al–2Ba–2Ca Alloy (ABaX422)

Effects of Initial δ Phase on Creep Behaviors and Fracture Characteristics of a Nickel‐Based Superalloy

Understanding the High Creep Resistance of MRI 230D Magnesium Alloy through Nanoindentation and Atom Probe Tomography

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