A New DTA Approach for Verifying Precipitate Solvus in Inconel Alloy 718

Abstract

Using differential thermal analysis (DTA) to determine solvus temperature of precipitated phases in a Nb-hardened superalloy, such as alloy 718, is relatively difficult. The precipitation reaction is not significantly pronounced, and the baseline of a DTA thermogram is not clearly defined. A new approach was employed in this study, which utilized a solution-treated Inconel alloy 7 18 as the reference instead of the conventional alumina. The samples for analysis were preaged at various temperatures to develop specific precipitate phases. The DTA thermograms showed a well-defined baseline because of similar alloy chemistry and heat capacity between the sample and the reference. The offset of thermal peaks associated with precipitate dissolution can be accurately determined.

The effect of prior annealing on high temperature flow properties of and microstructural evolution in SPF grade IN718 superalloy

“…Such precipitates in IN718 superalloy were identified to be carbides. This is also supported by the TTP (temperature-time-precipitation) curves for different precipitates in the IN718 superalloy [15]. The appearance of these precipitates in the gage section and their near absence in the shoulder section suggest that the precipitation process is favored by deformation mechanism.…”

Some features of anisothermal solid-state transformations in alloy 718

“…4, is reported in Fig. 14 where it is compared to the data from the literature [15][16][17][18][19][20][21][22].…”

Measurement of high temperature phase stability and thermophysical properties of alloy 740

“…2,7,8,10,16,22 It has been noticed that the dissolution temperatures of c9 and g phases are strongly dependent on Al, Ti and Nb content respectively. 8,10 The dissolution temperature of c9 phase increases with Al content; however, it decreases with Ti and Nb additions.…”