Accelerated degradation rate of high-strength Mg-4Y-1Zn alloy by Cu addition for degradable bridge-plug applications

2020 ◽  
Vol 111 (10) ◽  
pp. 872-875
Author(s):  
Baosheng Liu ◽  
Gehang Dong ◽  
Xiaoxia Ren ◽  
Yuezhong Zhang ◽  
Yinghui Wei
Keyword(s):  
Degradation Rate ◽  
Corrosion Potential ◽  
High Strength ◽  
Compressive Properties ◽  
Rapid Degradation ◽  
Lpso Phase ◽  
Accelerated Degradation ◽  
Long Period ◽  
Stacking Order ◽  
High Fraction

Abstract To find good candidate materials for degradable bridgeplugs used in shale oil or gas exploitation, a novel hot extruded Mg-4Y-1Zn-1Cu alloy with long period stacking order (LPSO) phase and excellent mechanical properties and rapid degradation rate was fabricated. Compared with the Mg-4Y-1Zn alloy, the compressive properties of Mg-4Y- 1Zn-1Cu alloy are dramatically enhanced by adding Cu, with a compressive strength of 480 MPa, which can be attributed to the formation of fine-grains and the strengthening LPSO phase distributed within the substrate. Furthermore, Mg-4Y-1Zn-1Cu alloy shows a rapid degradation rate as demonstrated by immersion tests and polarization curves, with about 30 times higher corrosion rate than Mg- 4Y-1Zn alloy, which can be attributed to the 14H-type LPSO phase containing Cu with high corrosion potential and high fraction grain boundaries.

Fine-Grained Structure in Extruded Magnesium Alloy with Long-Period Stacking Order Phase

2007 ◽  
Vol 561-565 ◽  
pp. 905-908
Author(s):  
Tatsuya Morikawa ◽  
Daisuke Kinoshita ◽  
Yoshihito Kawamura ◽  
Kenji Higashida
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Cast Alloy ◽  
High Strength ◽  
Lpso Phase ◽  
Fine Grained ◽  
Long Period ◽  
Stacking Order ◽  
Fine Grained Structure ◽  
Warm Extrusion

Microstructures developed by warm extrusion for Mg97Zn1Y2 alloy including long-period stacking order (LPSO) phase have been investigated using SEM and TEM. The extruded magnesium alloy with LPSO phase exhibits high strength and sufficient ductility. Such superior mechanical properties appear by warm extrusion around the temperature of 623K. The microstructure of the extruded alloy consists of matrix of fine-grained hcp phase and elongated grains with fine-lamellae including LPSO phase. The grain size of hcp matrix was about 1μm, indicating that remarkable grain refinement was occurred by extrusion since the grain size of as-cast alloy was about 500μm. Special attention has been paid on the enrichment of solutes at stacking faults and grain boundaries in the fine-grained matrix, which would contribute not only to the strengthening but also to the stability of fine-grained structure because of its role of an inhibiter against grain coarsening.

Effect of Long-Period Stacking Order Phase and α-Mg Phase on Strength and Ductility of Mg-Zn-Y Alloy

2012 ◽  
Vol 706-709 ◽  
pp. 1237-1242 ◽  
Author(s):  
Masafumi Noda ◽  
Yoshihito Kawamura
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
High Temperatures ◽  
Mg Alloys ◽  
Tensile Yield Strength ◽  
Block Type ◽  
Lpso Phase ◽  
Long Period ◽  
Stacking Order ◽  
Type Phase

Mg alloys are lightweight structural alloys that normally have a good castability and machinability as well as an excellent specific strength and rigidity. However, the mechanical properties of Mg alloys are inferior to those of Al alloys, and their range of industrial applications is limited. Recently, Mg–Zn–Y alloy has been found to show a high tensile yield strength with a good elongation. The alloy has a long-period stacking order (LPSO) phase as the secondary phase in an α-Mg phase. In general, the tensile yield strengths of LPSO-type Mg alloy are known to be markedly enhanced by the formation of kink bands in the LPSO phase and by microstructural refinement of the α-Mg phase during plastic deformation. The separate roles of the LPSO phase and the α-Mg phase in relation to the mechanical properties of high-strength LPSO-type Mg alloy were investigated at ambient and high temperatures. For high strengths at ambient and high temperatures, it was important that the α-Mg phase consisted of a fine-grain region and a nonrecrystallized region, and that the LPSO phase remained as a block-type phase. On the other hands, it was necessary to change the LPSO phase from a block-type phase into a plate-type phase by heat treatment before tensile testing to improve the ductility of the alloy while maintaining its tensile yield strength. Microstructural control of the LPSO phase and the α-Mg phase is necessary to obtained Mg–Zn–Y alloy with superior mechanical properties at ambient-to-high temperatures.

Thermal Stability and Mechanical Properties of Extruded Mg-Zn-Y Alloys with Long-Period Stacking Order Phase

2010 ◽  
Vol 654-656 ◽  
pp. 611-614 ◽  
Author(s):  
Masafumi Noda ◽  
Yoshihito Kawamura
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Strength ◽  
Grain Boundary Sliding ◽  
Temperature Deformation ◽  
Kink Bands ◽  
Lpso Phase ◽  
Fine Grained ◽  
Stacking Order ◽  
Boundary Sliding

Magnesium alloys are very attractive in such applications as automotive and aerospace. However, the mechanical properties of Mg alloys are inferior to those of Al alloys, and this limits their range of applications. In the present study, effects of annealing on the mechanical properties and the thermal stability of the microstructure in LPSO Mg-Zn-Y extruded alloys were investigated. Even when elongation showed 10% with having maintained high strength to annealing temperature at 573 K for 3.6 ks, and this alloy extended annealing time for 1.0 kh, LPSO phase did bent and was able to confirm kink bands. On the other hand, α-Mg phase was fine structure without pronounced grain growth. In elevated temperature deformation of as extruded and annealed materials, LPSO phase did finely dispersed to α-Mg phase by grain boundary sliding of α-Mg phase, but fracture did not occurred in the interface between LPSO and α-Mg phases. Kink bands introduced in LPSO phase during plastic deformation and fine-grained α-Mg phase were important to obtained of high strength and ductility.

scholarly journals Micro-Kinking of the Long-Period Stacking/Order (LPSO) Phase in a Hot-Extruded Mg97Zn1Y2 Alloy

2013 ◽  
Vol 54 (5) ◽  
pp. 698-702 ◽  
Author(s):  
Daisuke Egusa ◽  
Michiaki Yamasaki ◽  
Yoshihito Kawamura ◽  
Eiji Abe
Keyword(s):  
Lpso Phase ◽  
Long Period ◽  
Stacking Order

Accelerated Degradation Potential of Selected Herbicides in the Southeastern United States

1987 ◽  
Vol 1 (4) ◽  
pp. 350-358 ◽  
Author(s):  
Clyde C. Dowler ◽  
Luz R. Marti ◽  
Craig S. Kvien ◽  
Horace D. Skipper ◽  
Dewitt T. Gooden ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Soil Microorganisms ◽  
Southeastern United States ◽  
Biologically Active ◽  
Rapid Loss ◽  
Rapid Degradation ◽  
Soil Sterilization ◽  
Accelerated Degradation ◽  
Primary Mechanism ◽  
Previously Treated

The influence of previous herbicide applications on the degradation rate of butylate [S-ethyl bis (2-methylpropyl)carbamothioate], EPTC (S-ethyl dipropyl carbamothioate), alachlor [2-chloro-N-(2,6-diethyl-phenyl)-N-(methoxymethyl)acetamide], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] was measured. Degradation studies were conducted on soils with zero to eight previous applications of butylate, zero and six consecutive annual applications of alachlor, and zero to seven previous applications of metolachlor. Previous applications of alachlor or of metolachlor did not affect the rate of degradation when the same herbicide was reapplied. Soils with previous butylate-use history had more rapid degradation of butylate or EPTC than soils with no previous butylate applications. Because soil sterilization reduced14CO2evolution to a low level, soil microorganisms could be the primary mechanism of butylate degradation. There was no difference between butylate or EPTC degradation rate in soils treated previously with butylate. Butylate could not be detected 28 days after treatment in soils previously treated with butylate, whereas soils not previously treated with butylate still contained biologically active butylate. Dietholate (O,O-diethylO-phenyl phosphorothioate) added to butylate generally reduced the rate of butylate degradation in soils previously treated with butylate, but the butylate concentration always was lower in soils treated previously with butylate than in soils without previous butylate applications. Weed control in the field showed rapid loss of butylate and EPTC in soils with previous butylate treatment and that dietholate reduced the rate of butylate and EPTC degradation.

The Clustering of Zn6Y9 and its Predominant Role in Long Period Stacking Order Phases in Mg-Zn-Y Alloys: A First-Principles Study

2013 ◽  
Vol 749 ◽  
pp. 569-576 ◽  
Author(s):  
Shang Yi Ma ◽  
Li Min Liu ◽  
Shao Qing Wang
Keyword(s):  
First Principles ◽  
Building Block ◽  
Stacking Fault ◽  
First Principles Calculations ◽  
Predominant Role ◽  
Lpso Phase ◽  
Local Structures ◽  
Long Period ◽  
Stacking Order ◽  
The Ideal

The local structures of Zn and Y in the long period stacking order (LPSO) phase in Mg-Zn-Y system were investigated by first principles calculations in details. The clustering of Zn and Y atoms ranging from single stacking fault layer to four consecutive layers was explicitly demonstrated. The calculations indicate that Zn and Y atoms prefer clustering in the form of Zn6Y9 embedding in ABCA-type building block to the random or ordered arrangements of Zn and Y atoms being enriched in two stacking fault layers. The cluster of Zn6Y9 can be regarded as the ideal stoichiometric component of LPSO and it plays a predominant role in the LPSO phases. The formation of LPSO phases is highly associated with the Zn6Y9 cluster and its derivatives.

scholarly journals Analysis of the In Situ Crack Evolution Behavior in a Solid Solution Mg-13Gd-5Y-3Zn-0.3Zr Alloy

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 36
Author(s):  
Yaqin Yang ◽  
Chongli Mu ◽  
Zhongjian Han ◽  
Jian Xu ◽  
Baocheng Li
Keyword(s):  
Solid Solution ◽  
Stress Concentration ◽  
High Performance ◽  
Solution Treatment ◽  
High Strength ◽  
Lpso Phase ◽  
Stacking Order ◽  
Micro Cracks ◽  
Evolution Behavior

The low plasticity of high strength Mg-Gd-Y alloy has become the main obstacle to its application in engineering. In this paper, the origin, propagation and fracture processes of cracks of a solution of treated Mg-13Gd-5Y-3Zn-0.3Zr alloy were observed and studied with scanning electron microscopy (SEM) in an in situ tensile test to provide theoretical references for the development of a new high-performance Mg-Gd-Y alloy. The results showed that there was still some bulk long period stacking order (LPSO) phase remaining in solid solution Mg-13Gd-5Y-3Zn-0.3Zr alloy. Most importantly, it was found that the locations of micro-cracks vary with the different solution treatment processes, mainly including the following three types. (1) At 480 × 10 h and 510 °C × 10 h, much bulk LPSO phase with higher elastic modulus remains in the alloy, which can lead to micro-cracks in the LPSO phase due to stress concentration. (2) At 510 °C × 13 h and 510 °C × 16 h, the phase structure of bulk LPSO changes, and the stress concentration easily appears at the LPSO/α-Mg interface, which leads to micro-cracks at the interface. (3) At 510 °C × 19 h and 510 °C × 22 h, the grain size increases, and the stress concentration is obvious at the grain boundary of coarse grains, which leads to the formation of micro-cracks.

Multimodal Microstructure Evolution in Wrought Mg-Zn-Y Alloys with High Strength and Increased Ductility

2010 ◽  
Vol 654-656 ◽  
pp. 615-618 ◽  
Author(s):  
Michiaki Yamasaki ◽  
Kenji Hashimoto ◽  
Koji Hagihara ◽  
Yoshihito Kawamura
Keyword(s):  
Microstructure Evolution ◽  
Extrusion Direction ◽  
High Strength ◽  
Phase Region ◽  
Deformation Bands ◽  
Cast State ◽  
Lpso Phase ◽  
Long Period ◽  
Effective Dispersion ◽  
Coarse Grains

High strength and ductile Mg96Zn2Y2 (at%) alloys with multi-modal microstructure are developed. Microstructure of the extruded Mg96Zn2Y2 alloy consists of three regions; the dynamically recrystallized -Mg fine-grains region, the hot-worked -Mg coarse-grains region elongated along extrusion direction, and the long-period stacking ordered (LPSO) phase region with kink deformation bands. Bimodal microstructure evolution in -Mg matrix is influenced by the morphology of the LPSO phase in the as-cast state, therefore, the effect of secondary dendrite arm spacing in cast state on the microstructure evolution and mechanical properties of the extruded Mg-Zn-Y alloy is investigated. An increase in the dynamically recrystallized grains improves ductility of the extruded alloys; the effective dispersion of the LPSO phase enhances strengthening of the alloy.

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