Flow stress and elongation of superplastic deformation in La{sub 55}Al{sub 25}Ni{sub 20} metallic glass
The authors have investigated the flow stress and elongation of superplastic deformation in a La{sub 55}Al{sub 25}Ni{sub 20} (at%) metallic glass that has a wide supercooled liquid region of 72 K before crystallization. The superplasticity that appeared in the supercooled liquid region was generated by the Newtonian viscous flow that exhibits the m value of unity. The elongation to failure was restricted by the transition of the Newtonian flow to non-newtonian one and the crystallization during deformation. They succeeded in establishing the constitutive formulation of the flow stress in the supercooled liquid region. its formulation was expressed very well by a stretched exponential function {sigma}{sub flow} = D{dot {var_epsilon}} exp (H*/RT) [1-exp(E/{l_brace}{var_epsilon} exp (H**/RT){r_brace}{sup 0.82})]. Formulations describing the elongation to failure in constant-strain-rate and constant-crosshead velocity tests were, moreover, established. It was found from the simulation that the maximum elongation in the constant-strain-rate reached more than 10{sup 6}% which was two orders of magnitude larger than that in the constant-crosshead-velocity test.
- Research Organization:
- Tohoku Univ., Sendai (JP)
- OSTI ID:
- 20104688
- Country of Publication:
- United States
- Language:
- English
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