Surface Tension, Viscosity, and Selected Thermophysical Properties of Ti48Al48Nb2Cr2, Ti46Al46Nb8, and Ti46Al46Ta8 from Microgravity Experiments

Abstract

The surface tension and the viscosity of the alloys Ti48Al48Nb2Cr2, Ti46Al46Nb8, and Ti46Al46Ta8 are measured with the oscillating drop technique in an electromagnetic levitation device under reduced gravity conditions on board a parabolic flight airplane. The surface tensions as a function of temperature are obtained as σ(T) = (1.19 ± 0.02 − 3.80 × 10−4 (T − 1856 K)) Nm−1 for Ti46Al46Nb8, σ(T) = (1.21 ± 0.02 − 2.69 × 10−4 (T − 1879 K)) Nm−1 for Ti46Al46Ta8, and σ(T) = (1.20 ± 0.02 − 3.96 × 10−4 (T − 1776 K)) Nm−1 for Ti48Al48Nb2Cr2, concentrations in atomic per cent. The viscosities at the liquidus temperatures are obtained as η(Tl) = 6.62 mPa.s, η(Tl) = 6.9 mPa.s, and η(Tl) = 5.8 mPa.s in the same order. All processed specimens are solidified at an undercooling of ΔTu = 220 ± 30 K. In addition, the solidus and liquidus temperatures and the enthalpies of fusion are determined by calorimetry. From the large undercooling and the enthalpy of fusion, the average specific heat capacity at an undercooling of 120 K is obtained as cP(av) = 1.30 ± 0.20 J (kg)−1 for all alloys. The thermal expansion between the room and solidus temperatures is measured by dilatometry.

Precise Measurements of Thermophysical Properties of Liquid Ti–6Al–4V (Ti64) Alloy On Board the International Space Station

“…[24] Density and surface tension of liquid Ti64 was obtained by electromagnetic levitation by Egry et al on ground and under microgravity conditions. [21] The electromagnetic levitation technique was already successfully applied on other engineering alloys, such as on Ti-Al alloys (Wunderlich et al [28] ) during parabolic flights (PF), on Ni-based superalloys during PF (Higuchi et al [29] ), and on board the ISS (Mohr et al [30] ).…”

Thermophysical Properties of Advanced Ni‐Based Superalloys in the Liquid State Measured on Board the International Space Station

“…Containerless processing using electromagnetic levitation under microgravity can be performed on board of parabolic flights. [26][27][28] But the limited time of microgravity (typically 20 s) per parabola limits the measurement precision, as well as the type of measurements that can be performed. The International Space Station (ISS), in contrast, offers a long duration of microgravity which enables the measurement cycles to be as long as 20 min (limited only by the duration of the signal link to the ISS).…”

“…Containerless processing using electromagnetic levitation under microgravity can be performed on board of parabolic flights . But the limited time of microgravity (typically 20 s) per parabola limits the measurement precision, as well as the type of measurements that can be performed.…”

Investigating Thermophysical Properties Under Microgravity: A Review

“…www.advancedsciencenews.com www.aem-journal.com liquid phase. Several thermophysical property measurements on γ-Ti-Al alloys were obtained on parabolic flights, [58] and as such, these alloys are predestined for processing with the ISS-EML for thermophysical property measurements in the liquid phase. The Ti-47.5Al-2Cr-2Nb alloy was processed successfully on board the ISS.…”

“…[52] Thermophysical property measurements by conventional container-based methods are not possible in this temperature range. New high-strength Ti-aluminide alloys have been explored recently, where solidification and phase selection, [53] grain refinement, [54] casting simulations, [55] and the measurements of thermophysical properties [52,[56][57][58] have been in focus. This allows the production of advanced turbine blades for jet engines and other functional machinery parts reaching high strength levels at low density.…”