Densification of rapidly solidified titanium aluminide powders—II. The use of a sensor to verify hiring models

Abstract

An eddy-current sensor was used to monitor consolidation of γ-titanium aluminide powder, in situ, during hot isostatic pressing (HIP). The resulting data was then compared with predictions generated from a model developed by Helle, Easterling and Ashby. A major finding was that significant densification occurred during the pressurization phase of the HIP cycle. Agreement was extremely good between experiment and theory, although asymptotic errors were found in the model when approaching full density. Discrepancies also arose at 1223 K and short times, between the continuous sensor data and interrupted cycle density measurements. The transformation from metastable α 2-γ powders to a single phase γ microstructure was suggested as the origin of the discrepancy, which is not currently considered in the models. A useful method is also suggested by which the sensor may estimate the sample density on-line, using mathematical models to filter the sensor data.