A study on Al 2219 alloy precipitate growth rates by non-linear ultrasonic technique

A non-linear ultrasonic study has been carried out to characterise the variation in precipitation phase. An age-hardenable aluminium alloy (2219) has been taken as a model alloy for the present investigation. It is shown that there is a strong correlation between the change in the non-linear coefficient and the change in the precipitated phase. The observed variations in the non-linear ultrasonic parameter have been explained by modifying an existing dislocation-coherent precipitate interaction model for the generation of harmonics in order to account for a weaker dislocation-semicoherent precipitate interaction. In general, the model proposed can be applicable to all precipitation-hardenable alloy systems undergoing coherent to incoherent precipitate phase transition.