Superplasticity in Nb3Al/Nb In Situ Composites

1999 ◽  
Vol 601 ◽  
Author(s):  
S. Hanada ◽  
W. Fang
Keyword(s):  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Al Alloy ◽  
Two Phase ◽  
Dislocation Glide ◽  
In Situ Composite ◽  
Al Content ◽  
Boundary Sliding ◽  
Equiaxed Grains

AbstractMicrostructures of a binary Nb-15.8at%Al alloy ingot were controlled by isothermal forging and heat treatment to produce equiaxed, fine grains of Nb3Al and Nb solid solution (Nb33). Nb3Al/Nb33 two phase alloy (in-situ composite) is found to exhibit superplasticity especially when one of the constituent phases, Nb33, is supersaturated. During superplastic deformation Nb33 transforms to Nb3Al, and Al content in Nb33 decreases. After superplastic deformation the microstructure consisting of equiaxed grains is left unchanged, although a slight grain growth is observed. It is suggested that stress induced by grain boundary sliding is effectively accommodated through dislocation glide and climb in the soft Nb33

Deformation Behavior of Ti-6Al-4V and Ti-6.85Al-1.6V Alloy with a Globular Microstructure

2005 ◽  
Vol 475-479 ◽  
pp. 2965-2968 ◽  
Author(s):  
Jeoung Han Kim ◽  
S. Lee Semiatin ◽  
Chong Soo Lee
Keyword(s):  
Grain Boundary ◽  
Inelastic Deformation ◽  
Deformation Theory ◽  
Grain Boundary Sliding ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Junction Region ◽  
Two Phase ◽  
Dislocation Glide ◽  
Boundary Sliding

The high temperature deformation mechanisms of two phase a+b alloy and a near-a alloy were investigated, and compared within the framework of inelastic-deformation theory. For this purpose, load-relaxation tests were conducted on the two alloys at temperatures of 750~900°C. The flow stress-vs.-strain rate curves for both alloys were well fit with inelastic deformation equations describing dislocation glide and grain boundary sliding. The amount of grain boundary sliding resistance was higher in the near-a alloy rather than the two phase a+b alloy due to difficulty in stress relaxation at triple junction region.

High Temperature Deformation of a Nb-Ti-Al Alloy With σ+γ Microstructure

1994 ◽  
Vol 364 ◽  
Author(s):  
Fereshteh Ebrahimi ◽  
Bernardo J. G. DeAragao
Keyword(s):  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Al Alloy ◽  
Flow Curves ◽  
Two Phase ◽  
Σ Phase ◽  
Heat Treated ◽  
Boundary Sliding

AbstractAn alloy with composition 27Nb-33Ti-40Al (at. %) was heat treated to produce a fine two-phase microstructure of σ (Nb2Al) and γ (TiAl) phases. This microstructure exhibited a peak in the flow curves obtained in the strain rate range 5 × 10−4 to 5 × 10−6s−1 at 1000°C, with a stress exponent of 3. The deformation occurred by dislocation activity and twinning accompanied by dynamic recrystallization of the γ-phase and extensive grain boundary sliding of the σ-phase, which resulted in the separation and fragmentation of the latter phase.

scholarly journals Stereographic Analysis of Grain Boundary Sliding in Superplastic Deformation of Alumina-Zirconia Two Phase Ceramics

1999 ◽  
Vol 63 (3) ◽  
pp. 333-340 ◽  
Author(s):  
Satoru Ishihara ◽  
Tsuneyuki Tanizawa ◽  
Koutarou Akashiro ◽  
Norio Furushiro ◽  
Shigenori Hori
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Two Phase ◽  
Boundary Sliding

A Study on Superplastic Behavior and Microstructural Evolution of an Isothermally Forged TiAl Based Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 463-466
Author(s):  
Hua Ding ◽  
D. Song ◽  
Z.Q. Pan ◽  
C.P. Zhang ◽  
J.Z. Cui
Keyword(s):  
Strain Rate ◽  
Superplastic Deformation ◽  
Boundary Migration ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Sensitivity Index ◽  
Superplastic Behavior ◽  
Strain Rate Sensitivity Index ◽  
Boundary Sliding ◽  
Equiaxed Grains

Superplastic behavior and microstructure evolution of an isothermally forged Ti-47Al-1Cr-1V-1.5Mo-1.5Nb alloy were investigated. The results showed that the strain rate sensitivity index, m, increased with strain during the superplastic deformation, and it kept as a constant when the strain reached a certain value. The maximum value of m was 0.53 at 900°C and strain rate of 5x10-4 s-1. During the superplastic deformation, the as received material with lamellae and subgrains were refined due to dynamic recrystallization, and small and equiaxed grains with high angle boundaries were formed, creating a better condition for superplastic deformation. Grain boundary sliding and boundary migration were the main superplastic deformation mechanisms and slip and twining were also very important during the superplastic deformation of the alloy.

scholarly journals Stereographic Analysis of Grain Boundary Sliding in Superplastic Deformation of Alumina-Zirconia Two Phase Ceramics

1999 ◽  
Vol 40 (10) ◽  
pp. 1158-1165 ◽  
Author(s):  
Satoru Ishihara ◽  
Tsuneyuki Tanizawa ◽  
Koutarou Akashiro ◽  
Norio Furushiro ◽  
Shigenori Hori
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Two Phase ◽  
Boundary Sliding

Effect of Aging Treatment on Mechanical Properties and Electrical Conductivity of Cu-5.7%Cr In Situ Composite Produced by Equal Channel Angular Pressing

2012 ◽  
Vol 560-561 ◽  
pp. 344-348 ◽  
Author(s):  
Wei Wei ◽  
Kun Xia Wei ◽  
Igor V. Alexandrov ◽  
Qing Bo Du ◽  
Jing Hu
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Equal Channel Angular Pressing ◽  
Aging Treatment ◽  
In Situ Composite ◽  
Angular Pressing ◽  
Peak Aging ◽  
Average Size ◽  
Equiaxed Grains

The effect of aging treatment on mechanical properties and electrical conductivity of Cu-5.7%Cr in situ composite produced by equal channel angular pressing (ECAP) was investigated here. The rotation and spreading of Cr particles was observed in Cu-5.7%Cr alloy during the ECAP, resulting in long thin in situ filaments. The equiaxed grains of the Cu phase with an average size of 200 nm were developed after eight passes of ECAP. When aging at 400~450 °C for 1 h, Cu-5.7%Cr composite after ECAP shows the maximum microhardness, and the electrical conductivity is larger than 70% of IACS. At 400 °C, the peak aging time appears for 0.5~2 h, dependent on the pre-strain for all ECAP samples. With the increase of ECAP passes, the enhancement of tensile strength due to the aging treatment declines, and even shows negative after eight passes of ECAP. The combination of ECAP and aging treatment would be a promising process to balance mechanical properties and electrical conductivity of Cu-5.7%Cr composite.

Effect of Superplastic Deformation on the Properties of Zirconia Dispersed Alumina Nanocomposite

2007 ◽  
Vol 551-552 ◽  
pp. 527-532 ◽  
Author(s):  
Guo Qing Chen ◽  
Shao Hua Sui ◽  
X.D. Wang ◽  
Wen Bo Han
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Superplastic Deformation ◽  
Critical Dimension ◽  
Grain Boundary Sliding ◽  
Transformation Toughening ◽  
Grain Coarsening ◽  
Boundary Sliding ◽  
Phase Transformation Toughening

In this paper constrained extrusion of the zirconia dispersed alumina nanocomposite under superplastic conditions was conducted. The mechanical properties of deformed material were studied and its results were compared with those of the initial materials. The microstructure evolution during superplastic deformation was also analyzed. The results demonstrated that after superplastic extrusion the flexural strength, relative density, Vickers hardness as well as fracture toughness of the material increased noticeably. The flexural strength of the deformed composite even retained at a high value of 310MPa at 800°C. The fracture toughness of the material increased from 6.92 MPa·m1/2 to 8.87 MPa·m1/2 after deformation. After superplastic extrusion due to grain boundary sliding and the compressive stress state, the internal porosities in as-sintered materials were eliminated. During extrusion with grain coarsening the effect of t-ZrO2 to m-ZrO2 transformation toughening increased because more zirconia grains reached the critical dimension. Although grain coarsening may cause the decrease of the fracture toughness in some extent, the phase transformation toughening and strengthening dominated. As a result, the mechanical properties of the deformed material were improved.

In-situ observation of cooperative grain boundary sliding and migration in the nano-twinned nanocrystalline-Au thin-films

2020 ◽  
Vol 180 ◽  
pp. 97-102 ◽  
Author(s):  
Qizhen Li ◽  
Lihua Wang ◽  
Jiao Teng ◽  
Xiaolu Pang ◽  
Xiaodong Han ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
In Situ Observation ◽  
Boundary Sliding ◽  
Au Thin Films ◽  
And Migration
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