High strain rate superplasticity

For the purpose of discussion. Table 2 summarizes HSRS data obtained from a number of Al alloys and composites. It was first noted by Nieh et al [5] that the optimum temperature for high strain rate superplasticity in an alloy is either above or close to the solidus temperature. This led them to suggest that the presence of a liquid phase might have contributed to the observed HSRS. 

T.G. Nieh, J. Wadsworth, and T. Imai, "A Rheological View of High-Strain-Rate Superplasticity in Metallic Alloys and Composites," Scr. Metall. Mater., 26(5) 703 (1992). 

T. G. Nieh, J. Wadsworth, and K. Higashi, "High Strain Rate Superplasticity in Metals and Composites," in Transaction of the Materials Research Society of Japan Vol 16B - Composites, Grain Boundaries and Nanophase Materials, pp. 1027-1032, M. Sakai, M. Kobayashi, T. Suga, R. Watanabe, Y. Ishida, and K. Niihara ed., Elsevier Science, Netherland, (1994). 

B.Q. Han, K.C. Chan, T.M. Yue, and W.S. Lau, "A Theoretical Model for High-Strain-Rate Superplastic Behavior of Particulate Reinforced Metal Matrix Composites," Scr. Metall. Mater., 33 925 (1995). 

In the immediate future, the main objective in ceramic superplasticity will be the search of the right conditions to achieve high strain rate superplasticity (HSRS) ((e > 1CT2 s 1). Although this phenomenon has been found in several ceramic compounds and several inputs have been outlined to achieve it, we are still far from knowing what to do to obtain this effect systematically. This HSRS will enlarge the applications for ceramics. 

Morita, K., Hiraga, K., and Sakka, Y., High-strain rate superplasticity in Y203-stabilized tetragonal Zr02 dispersed with 30 vol% Mg A1204 spinel , J. Am. Ceram. Soc, 2002, 85, 1900-2. 

Komura Sh., Berbon P.B., Furukawa M., Horita Z., Nemoto M., Langdon T.G. (1998) High strain rate superplasticity in Al-Mg alloy containing scandium, Scripta Materialla 38, No. 12,1851-1856. 

HIGH STRAIN RATE SUPERPLASTIC BEHAVIOR OF Al-Li-Mg-Cu-Sc ALLOY SUBJECTED TO SEVERE PLASTIC DEFORMATION... 

High strain rate superplastic behavior of an Al-Li-Mg-Cu-Sc alloy... 

Studies performed at the University of Missouri-Rolla in conjunction with Rockwell Scientific have shown FSP to produce a hne-grain-size material and create low-temperature, high-strain-rate superplasticity in aluminum and titanium alloys. The PNNL is currently investigating the application of this FSP-induced superplasticity in the fabrication of large, integrally stiffened structures. 

Strain rate Scientihcally, the strain rate is an indication of the flow kinetics of the deformahon mechanism, whereas technologically, it has important implications for overall forming hme. A strain rate of 10 s has been deflned somewhat subjechvely as the transihon to high-strain-rate superplasticity (HSRS). The implicahon of HSRS is that components can be formed in minutes rather than the hours required at convenhonal forming rates. 

Friction Stir Processing as a Technology Enabler for New Concepts. Apart from the opportunity for achieving high-strain-rate superplasticity in commercial alloys, FSP offers several new opportunities as a technology enabler (Ref 44, 56). Some of these possibilities are briefly described as follows (Ref 44) ... 

R.S. Mishra and M.W. Mahoney, Friction Stir Processing A New Grain Refinement Technique to Achieve High Strain Rate Superplasticity in Commercial Alloys, Mater. Sci. Forum, Vol 357-359, 2001, p507-514... 

R.S. Mishra, Processing Commercial Aluminum Alloys for High Strain Rate Superplasticity, JOM, Vol 53 (No. 3), March 2001, p 23-26... 

M.W. Mahoney, R. Mishra, and T. Nelson, High Strain Rate Superplasticity in Thick Section 7050 Aluminum Created hy Friction Stir Processing, Proc. Third International Symposium on Friction Stir Welding, Sept 27-28, 2001 (Kobe, Japan), TWI, 2002... 

I. Charit, Z.Y. Ma, and R.S. Mishra, High Strain Rate Superplasticity in Aluminum Alloys via Friction Stir Processing, Advances in Superplasticity and Superplastic Forming, 2004 TMS Annual Meeting, March 14-18, 2004 (Charlotte, NC), 2004, p 201-209... 

T Imai, G L esperance, BD Hong, Y Tozawa. High strain rate superplasticity of T1B2 particulate reinforced aluminium alloy composite. J Mater Sci Lett 14 373, 1995. 

N. Kim, K. Hiraga, K. Morita, and Y. Sakka, A High-Strain-Rate Superplastic Ceramic, Nature 413, 288-291 (2001). 

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