Instrumented indentation of transforming and no-transforming phases in Cu-Al-Be shape memory alloys

S. MONTECINOS; A. CUNIBERTI; S.N. SIMISON

INTERMETALLICS

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2012 vol. 28 p. 58 - 64

0966-9795

The behavior of Cu-Al-Be alloys under instrumented indentation using a Berkovich tip was studied. The pseudoelastic effect was evidenced in the transforming beta Cu-Al-Be phase as a closed hysteresis loop between the unloading-reloading paths in the P-h curves and high depth recovery ratios. From series of indentations conducted in the (beta+γ2) specimens, it was found that the indentation response of the two phases is remarkably different. Unlike the pseudoelastic beta phase, g2 precipitates present an elastic-plastic behavior, obtaining a complete coincidence between the unload and reload path in the load-displacement curves, and a lower recovery capacity. An average contact pressure versus the penetration depth curve was estimated for each indentation curve, and results suggest that 8 GPa and 3 GPa can be considered an elastic limit for γ2 and beta phase respectively under Berkovich indenter stress state. The elastic modulus and hardness of both phases were estimated from load-displacement curves using the Oliver and Pharr method.