Measurement of the density and surface tension of Ni-based superalloys in the liquid and mushy states

Abstract

The densities of three Ni-based superalloys have been measured in both liquid and mushy states by both a modified sessile drop method (MSDM) and a modified pycnometric method (MPM) for alloys CMSX-4 and CM186LC, and for CMSX-10 alloy by MSDM only. The surface tensions of liquid CMSX-4, CM186LC, and CMSX-10 superalloys were measured using the sessile drop method. All measurements were carried out in a highly purified argon atmosphere with the oxygen partial pressure of less than 10 Ϫ19 MPa in the gas outlet. The densities of all superalloys in both liquid and mushy states were found to decrease with increasing temperature. The volume thermal expansion of each superalloy in the mushy state was found to be higher than that in the liquid state. The densities determined by different methods have been critically assessed and recommended values in both liquid and mushy states are given as a linear function of temperature for the three Ni-based superalloys. The surface tension of liquid CMSX-4 superalloy was found to decrease with increasing temperature, while that of liquid CMSX-10 superalloy increases with increasing temperature. The wetting behavior of liquid CM186LC on the alumina substrate was found (1) to differ significantly from that of CMSX-4 and CMSX-10 and (2) to vary with time. A HfO 2 -rich layer was found in the contact area of CM186LC with the alumina substrate, which could lead to some uncertainty in the value obtained for the surface tension determined for CM186LC.

Surface Tension and Viscosity of the Ni-Based Superalloys LEK94 and CMSX-10 Measured by the Oscillating Drop Method on Board a Parabolic Flight

“…Results of the relative length change, DL/L o , between RT and T sol are given in Table II. For CMSX-10, the density in the liquid phase was measured with the sessile drop by Mills et al [29] as q(T liq ) = 8.081 g cm À3 .…”

“…This values fall well within the range of temperature coefficients reported for the Ni-based superalloys. The surface tension of CMSX-10 was measured by Li et al [45] by the sessile drop method. At the liquidus temperature, a value of r(T liq ) = 1.79 Nm À1 was obtained.…”

Calculation of Thermophysical Properties of Ni-based Superalloys

“…Surface tension measurements have been reported (1) Li et al 5) using the sessile drop method for alloys CMSX4, CMSX10 and CM186 LC, (2) by Brooks et al 32) using the oscillating drop method for IN718 and (3) by Wunderlich and Fecht 11,28) using the oscillating drop method (parabolic flights) for alloys C263, IN738, MM247, the values of (dg/dT) for IN738 and MM247 LC seem excessively large. Li et al 5) pointed out that the reaction of Hf in CM186 LC with the alumina substrate led to a contact angle Ͻ90°w hich would lead to a less-reliable value for the surface tension of this alloy.…”

“…Li et al 5) pointed out that the reaction of Hf in CM186 LC with the alumina substrate led to a contact angle Ͻ90°w hich would lead to a less-reliable value for the surface tension of this alloy. In addition, surface tension measurements have been reported by various investigators using different techniques on one specific batch of CMSX4.…”

“…Li et al 5) reported contact angle (q) measurements of 155Ϯ5°at 1 700 K and 140Ϯ10°at 1 800 K for alloys CMSX4 and CMSX10 on Al 2 O 3 substrates but Hf in CM186 LC was found to react with the Al 2 O 3 substrate which resulted in values of qϽ85°.…”