Creep behavior in TiPdNi high temperature shape memory alloy

The focus of the current effort is to characterize the viscoplastic behavior in high temperature shape memory alloys and understand the impact of creep on their actuation characteristics. For this a Ti50Pd40Ni10 alloy was cast and hot rolled. Standard creep tests and isobaric thermal cycling tests were conducted on a custom test setup. The results from the thermomechanical tests indicate large irrecoverable strains due to creep. Varying thermally induced transformation cycling rates did not impact the transformation behavior in the SMA. From these observations, it can be suggested that the rate of thermal cycling can alter the impact of viscoplasticity on the actuators performance. However the creep behavior itself is decoupled from the transformation and does not impact the transformation or the rate independent irrecoverable strain generated.

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