Superplastic Behavior in Magnesium Alloy with Dispersion of Quasicrystal Phase Particle

2010 ◽  
Vol 433 ◽  
pp. 291-295
Author(s):  
Hidetoshi Somekawa ◽  
Alok Singh ◽  
Toshiji Mukai
Keyword(s):  
Phase Particle ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Mechanical Anisotropy ◽  
Micro Hardness ◽  
Superplastic Behavior ◽  
Fine Grained ◽  
Microstructure Observation ◽  
Boundary Sliding ◽  
High Possibility

Superplastic behavior was investigated using an extruded Mg-Zn-Y alloy with the dispersion of the quasicrystal phase particle in fine-grained matrix. Tensile tests showed that the low temperature superplasticity was behaved at a temperature of 473 K and maximum elongation was 462 % at 573 K in 1  10-5 s-1. The deformed microstructure observation showed that the dominant deformation process was grain boundary sliding. The present alloy also demonstrated a high possibility for secondary forming, such as superplastic forge forming. Furthermore, the forged alloy had a homogeneous microstructures, no mechanical anisotropy and uniform micro-hardness properties in any portion of a forged product.

Contributions of Grain Boundary Sliding and Solute Drag Creep to High-Temperature Ductility in Fine-Grained Polycrystalline 5083 Alloys

2014 ◽  
Vol 922 ◽  
pp. 360-365 ◽  
Author(s):  
Takashi Mizuguchi ◽  
Tsutomu Ito ◽  
Kota Kimura ◽  
Yasuhiro Tanaka
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Solute Drag ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Solid Solution Alloy ◽  
Friction Stir ◽  
Fine Grained ◽  
Elongation To Failure ◽  
Boundary Sliding

In this study, the high-temperature ductility of a fine-grained, polycrystalline 5083 solid solution alloy was investigated. The composition of the alloy in mass% was Al–4.5 Mg–0.68 Mn–0.19 Fe–0.13 Si–0.11 Cr. Grain refinement was effectively achieved in the stir zone by a friction stir process, and the grain size could be reduced to 3.7 μm. Tensile tests were performed at temperatures ranging from 643 to 743 K and strain rates ranging from 0.001 to 0.1 /s. The stress–strain curves showed that the flow stress continuously decreased until it reached a maximum value of stress and fractured after the initial strain hardening occurred. The value of elongation-to-failure was more than 100% when temperatures were greater than 693 K. The high ductility observed at this point can be referred to as superplastic-like elongation. This phenomenon has been reported in some Al–Mg alloys. The experimentally determined stress exponent (n value) and activation energy for deformation were about 2.5 and 123 kJ/mol, respectively. These results suggest that the grain boundary sliding, accompanied by solute drag motion of dislocations, was a rate controlling process for deformation.

Superplasticity in NiAl and NiAl-based alloys

2002 ◽  
Vol 17 (9) ◽  
pp. 2346-2356 ◽  
Author(s):  
J. J. Guo ◽  
X. X. Du ◽  
L. L. Zhou ◽  
B. D. Zhou ◽  
Y. Y. Qi ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Dynamic Recovery ◽  
Columnar Structure ◽  
Grain Boundary Sliding ◽  
Dislocation Slip ◽  
Directionally Solidified ◽  
Superplastic Behavior ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
Boundary Sliding

Superplastic deformation was realized on NiAl and NiAl-based alloys prepared by both common casting and directional solidification. Directionally solidified NiAl–27Fe–3Nb alloy as well as conventionally cast NiAl, NiAl–25Cr, NiAl–9Mo, NiAl–20Fe–Y.Ce, and NiAl–30Fe–Y alloys exhibited typical deformation characteristics shown in conventionally superplastic materials. NiAl and NiAl-based alloys could be divided into three categories depending on their different superplastic behavior: finely grained structure (NiAl–9Mo, NiAl–25Cr, NiAl–20.4Fe–Y.Ce, NiAl–30Fe–Y), coarsely grained structure (NiAl), and columnar structure (NiAl–27Fe–3Nb). The corresponding deformation mechanisms for fine-grained structure, coarsely grained structure, and columnar structure were grain boundary sliding or grain boundary sliding accompanied by dynamic recrystallization, dynamic recovery and recrystallization, and intragrain dislocation slip, respectively.

Microstructure and Mechanical Properties of Ni3Al-Ai2O3 Composites Produced by Hot Extrusion

1990 ◽  
Vol 194 ◽  
Author(s):  
C. G. McKamey ◽  
E. H. Lee
Keyword(s):  
Room Temperature ◽  
Hot Extrusion ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Diffusional Creep ◽  
Superplastic Behavior ◽  
Fine Grain ◽  
Boundary Sliding ◽  
Microstructural Studies ◽  
Better Than

AbstractHot extrusion of premixed charges of 10–20 vol% chopped A12O fiber and Ni3Al powder has resulted in composite alloys of near theoretical density. In tensile tests at room temperature, density-compensated yield strengths of some of these composite alloys are as good or better than those of as-cast Ni3Al without reinforcement; however strengths at 1000°C in vacuum are lower. The low strength at 1000°C and fine grain size (2–3/μm) suggest the presence of superplastic behavior and the accompanying diffusional creep and grain boundary sliding. This presentation discusses our findings to date and includes microstructural studies and tensile properties, both at room temperature in air and 1000°C in vacuum.

A Comparative Study on Superplasticity of Mg-Zn-Y-Zr Processed by ECAE and Hot Rolling

2007 ◽  
Vol 551-552 ◽  
pp. 203-208 ◽  
Author(s):  
Wei Neng Tang ◽  
Hong Yan ◽  
Rong Shi Chen ◽  
En Hou Han
Keyword(s):  
Hot Rolling ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Sensitivity Coefficient ◽  
Grain Boundary Sliding ◽  
Diffusional Creep ◽  
Dislocation Creep ◽  
Fine Grained ◽  
Microstructure Observation ◽  
Elongation To Failure

Superplastic deformation (SPD) behaviors of two fine-grained materials produced by ECAE and hot rolling methods have been contrastively studied in this paper. It is found that the optimum superplastic condition in as-ECAEed material was at 350°C and 1.7×10-3s-1 with elongation to failure about 800%; while in as-rolled material, the largest elongation to failure about 1000% was obtained at 480°C and 5.02×10-4s-1. Microstructure observation showed that grain evolution and cavitation behavior were different in these two materials during superplastic deformation. The controlled mechanisms for superplasticity, i.e. grain boundary sliding (GBS), dislocation creep and diffusional creep, at different deformation conditions were discussed in terms of strain rate sensitivity coefficient, stress exponent and activity energy.

Microstructure and Mechanical Properties of a 1.6C (pct) Ultra-Fine Grained Ultra-High Carbon Steel

2011 ◽  
Vol 682 ◽  
pp. 131-137
Author(s):  
Ya Jun Fan ◽  
Ji Min Cao ◽  
Wei Min Wang ◽  
Yong Ning Liu
Keyword(s):  
Carbon Steel ◽  
Lower Cost ◽  
High Carbon Steel ◽  
Ferrite Matrix ◽  
Grain Boundary Sliding ◽  
High Carbon ◽  
Fine Grained ◽  
Engineering Steel ◽  
Deformation Mechanics ◽  
Boundary Sliding

With massive trials, spheroidized by austeniting at 810°C and cooling by 1°C/min, a 1.6C (pct) Ultra-high Carbon Steel shows a microstructure of uniformly distributed fine carbides in the ultra-fine ferrite matrix. The grain size of ferrite matrix and spheroidized carbides are about 5um and 0.1～2um, respectively. Further investigation by TEM shows that much dislocation together with twins is obtained for the UHCS, and generally finer grains have higher dislocation density. The spheroidized steel exhibits high tensile strength of 910 MPa and high yielding strength of 653 MPa at room temperature, together with excellent elongation of 18.3%, which shows the UHCS can entirely satisfy certain grades of engineering materials and means the steel may substitute present engineering steel considering lower cost. Furthermore, the steel owns good high-temperature superplasticity, the elongation of 216% obtained at 800°C under a strain rate of 2.5×10-4. Initial analysis suggests that the superplastic deformation mechanics of the steel is grain boundary sliding and grain rotating (GBSR), coordinated by migration of dislocation.

High-Temperature Deformation of Magnesium ElektronTM 43

2012 ◽  
Vol 735 ◽  
pp. 93-100
Author(s):  
Alexander J. Carpenter ◽  
Anthony J. Barnes ◽  
Eric M. Taleff
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Superplastic Forming ◽  
Solute Drag ◽  
Grain Boundary Sliding ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Fine Grained ◽  
Boundary Sliding

Complex sheet metal components can be formed from lightweight aluminum and magnesium sheet alloys using superplastic forming technologies. Superplastic forming typically takes advantage of the high strain-rate sensitivity characteristic of grain-boundary-sliding (GBS) creep to obtain significant ductility at high temperatures. However, GBS creep requires fine-grained materials, which can be expensive and difficult to manufacture. An alternative is provided by materials that exhibit solute-drag (SD) creep, a mechanism that also produces elevated values of strain-rate sensitivity. SD creep typically operates at lower temperatures and faster strain rates than does GBS creep. Unlike GBS creep, solute-drag creep does not require a fine, stable grain size. Previous work by Boissière et al. suggested that the Mg-Y-Nd alloy, essentially WE43, deforms by SD creep at temperatures near 400°C. The present investigation examines both tensile and biaxial deformation behavior of ElektronTM 43 sheet, which has a composition similar to WE43, at temperatures ranging from 400 to 500°C. Data are presented that provide additional evidence for SD creep in Elektron 43 and demonstrate the remarkable degree of biaxial strain possible under this regime (>1000%). These results indicate an excellent potential for producing complex 3-D parts, via superplastic forming, using this particular heat-treatable Mg alloy.

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