scholarly journals Relationship Between High-Strain-Rate Superplasticity and Interface Microstructure in Aluminum Alloy Composites

1999 ◽  
Vol 5 (S2) ◽  
pp. 772-773
Author(s):  
J. Koike ◽  
K.E. Sickafus ◽  
T.E. Mitchell
Keyword(s):  
Aluminum Alloy ◽  
Liquid Phase ◽  
High Strain Rate ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Partial Melting ◽  
High Strain ◽  
Al Alloy ◽  
Scanning Calorimetry ◽  
Matrix Reinforcement

The Al alloy composites reinforced with Si3N4 or SiC have been reported to exhibit superplasticity at high strain rate of faster than 1x10−2 s−1. It has been shown in many aluminum alloy composites that the optimum superplastic temperature coincides with an incipient melting temperature. The coincidence suggests a contribution of the liquid phase to the superplasticity mechanism. This paper shows a direct evidence of partial melting along matrix grain boundaries and matrix-reinforcement interfaces. Based on the obtained results, the role of the liquid phase in the high-strain-rate superplasticity is discussed.The sample was Al-Mg (5052) alloy reinforced with 20vol% Si3,N4 particles, fabricated by a powder metallurgy process. The sample showed an excellent superplasticity under the conditions given in Table 1. Partial melting was confirmed to occur at 821 K by differentail scanning calorimetry. The microstructural changes during heating were observed in situ by TEM using a heating stage. The structure of interfaces and grain boundaries was observed by HREM. Chemical analysis was performed with EDS attached to VG-STEM.

Interface structure and solute segregation behavior in SiC/2124 and SiC/6061 Al composites exhibiting high-strain-rate superplasticity

2001 ◽  
Vol 16 (8) ◽  
pp. 2429-2435 ◽  
Author(s):  
Woo-Jin Kim ◽  
Dong-Wha Kum ◽  
Ha-Guk Jeong
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Partial Melting ◽  
High Strain ◽  
Interface Structure ◽  
Solute Segregation ◽  
Optimum Temperature ◽  
Scanning Calorimetry ◽  
Segregation Behavior ◽  
Reinforced Composite

Interface structure and solute-segregation behavior in the high-strain-rate superplastic SiCp/2124 and SiCp/6061 Al composites were investigated. Evidence for interfacial reaction between reinforcement and Al matrix, which was evident in the superplastic Si3N4p,w/2124 Al and Si3N4p,w/6061 Al composites, could not be detected in the current SiC-reinforced Al composites. Instead, strong solute segregation was observed at SiC/Al interfaces. Extensive formation of whiskerlike fibers was observed at the fractured surface of tensile samples above the critical temperature where particle weakening began to be seen. These results suggest that partial melting occurs at the solute-enriched region near SiC interfaces and is responsible for the particle weakening. The absence of reaction phase in the SiC-reinforced composite may explain why no endothermic peak for partial melting appears in its differential scanning calorimetry curve and why its optimum temperature for superplasticity is generally higher than that of the Si3N4-reinforced composite.

Critical assessments of accommodation process by liquid phase for superplastic flow in Si3N4/Al–Mg–Si metal matrix composites

1997 ◽  
Vol 12 (9) ◽  
pp. 2332-2336 ◽  
Author(s):  
Mamoru Mabuchi ◽  
Hajime Iwasaki ◽  
Ha-Guk Jeong ◽  
Kenji Hiraga ◽  
Kenji Higashi
Keyword(s):  
Liquid Phase ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Aluminum Matrix ◽  
Critical Conditions ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Stress Concentrations ◽  
Scanning Calorimetry

A liquid phase serves to relax stress concentrations caused by sliding at interfaces and grain boundaries in high-strain-rate superplasticity for aluminum matrix composites. However, the presence of a liquid phase does not always lead to high-strain-rate superplasticity because too much liquid causes decohesion at a liquid phase. The critical conditions of the optimum distribution, thickness, and volume in a liquid phase are discussed based on the observation results by differential scanning calorimetry and transmission electron microscopy. As a result, a very thin and discontinuous liquid phase is required both to assist relaxation of the stress concentrations and to limit decohesion at a liquid phase.

High Strain Rate Superplasticity in a Zr and Sc Modified 7075 Aluminum Alloy Produced by ECAP

2008 ◽  
Vol 584-586 ◽  
pp. 164-169 ◽  
Author(s):  
Krystof Turba ◽  
Premysl Malek ◽  
Edgar F. Rauch ◽  
Miroslav Cieslar
Keyword(s):  
Aluminum Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
7075 Aluminum Alloy ◽  
Fine Grained ◽  
Angular Pressing ◽  
Average Grain Size ◽  
Elongation To Failure

Equal-channel angular pressing (ECAP) at 443 K was used to introduce an ultra-fine grained (UFG) microstructure to a Zr and Sc modified 7075 aluminum alloy. Using the methods of TEM and EBSD, an average grain size of 0.6 1m was recorded after the pressing. The UFG microstructure remained very stable up to the temperature of 723 K, where the material exhibited high strain rate superplasticity (HSRSP) with elongations to failure of 610 % and 410 % at initial strain rates of 6.4 x 10-2 s-1 and 1 x 10-1 s-1, respectively. A strain rate sensitivity parameter m in the vicinity of 0.45 was observed at temperatures as high as 773 K. At this temperature, the material still reached an elongation to failure of 430 % at 2 x 10-2 s-1. These results confirm the stabilizing effect of the Zr and Sc additions on the UFG microstructure in a 7XXX series aluminum alloy produced by severe plastic deformation.

High strain rate compressive characterization of aluminum alloy/fly ash cenosphere composites

JOM ◽  
2011 ◽  
Vol 63 (2) ◽  
pp. 53-56 ◽  
Author(s):  
Dung D. Luong ◽  
Nikhil Gupta ◽  
Atef Daoud ◽  
Pradeep K. Rohatgi
Keyword(s):  
Aluminum Alloy ◽  
Fly Ash ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Fly Ash Cenosphere

Viscoplastic behavior of AA7075 aluminum alloy at high strain rate

2021 ◽  
Vol 35 (12) ◽  
pp. 5405-5413
Author(s):  
Keguo Zhang ◽  
Yang Cao ◽  
Jianlin An ◽  
Keyi Wang
Keyword(s):  
Aluminum Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain

Application of High-Strain-Rate Superplastic Zn-Al Alloy to Seismic Dampers and its Optimised Shape Design

2007 ◽  
pp. 583-590
Author(s):  
Atsumichi Kushibe ◽  
Yorinobu Takigawa ◽  
Kenji Higashi ◽  
Kazuo Aoki ◽  
Koichi Makii ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Shape Design ◽  
Al Alloy

Application to Seismic Dampers in High-Strain-Rate Superplastic Zn-Al Alloy

2005 ◽  
pp. 3055-3060
Author(s):  
Atsumichi Kushibe ◽  
Koichi Makii ◽  
L.F. Chiang ◽  
Tsutomu Tanaka ◽  
Masahide Kohzu ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Al Alloy
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