Containerless measurements of the liquid-state density of Ni–Al alloys for use as turbine blade materials

Abstract

Ni-Al alloys are good candidate materials for the turbine blades of high-efficiency gas turbines. The thermophysical properties of the liquid alloy are required for accurate modeling of the casting process. In this study, the densities of liquid Ni-Al alloys were measured over the entire composition range using the electromagnetic levitation technique under a static magnetic field. Surface oscillation and translational motion of the electromagnetically levitated droplet are suppressed by the static magnetic field, so an accuracy density can be obtained using the technique under a static magnetic field. Before the measurements, the liquidus temperatures of Ni-rich alloys were determined by differential scanning calorimetry. The liquidus temperatures were used as temperature calibration for the density measurements. For all of the compositions, the densities were measured with an experimental uncertainty of less than 1.9%, and they are a linear function of the temperature. The excess volume of the liquid alloys has a minimum value at 50 mol% Ni. The results are discussed from the viewpoint of the thermodynamics. The Ni-Al system shows a large negative excess volume with large negative enthalpy of mixing and excess Gibbs energy.

In‐situ observation of AlN formation from Ni‐Al solution using an electromagnetic levitation technique

“…The sample temperature was monitored by a single‐color pyrometer (LumaSense Technologies, IMPAC IGA140/MB25, 1.45‐1.8 µm). The pyrometer was calibrated with the liquidus temperature of each alloy, as indicated in Figure . After the molten sample maintains stability, the purified nitrogen gas (Matheson Tri‐Gas, Inc, Nanochem PuriFilter, PF‐25) was introduced into the sample with a flow rate of 0.3 L/min.…”

“…The pyrometer was calibrated with the liquidus temperature of each alloy, as indicated in Figure 2. 27 After the molten sample maintains stability, the purified nitrogen gas (Matheson Tri-Gas, Inc, Nanochem PuriFilter, PF-25) was introduced into the sample with a flow rate of 0.3 L/ min. The introduction of the gas causes the formation of AlN to occur on the sample surface.…”

“…Here, we have developed an in-situ observation system for solution growth of AlN crystal using an electromagnetic levitation (EML) in combination with an automated image processing pipeline 21 to quantify nucleation and growth. The EML technique is generally used for the measurement of thermophysical properties [22][23][24][25][26][27] or investigation of the solidification process [28][29][30] of metallic melts. In this paper, we describe the details of the in-situ observation system and the quantitative analysis of the AlN nucleation and growth from the Ni-Al solution using computer vision and materials data science methods.…”

Composition Dependence of Normal Spectral Emissivity of Liquid Ni–Al Alloys

“…The density of the liquid Ni-Al alloys was previously measured using PROSPECT. 7) Emissivity is an important parameter to understand the heat transfer phenomenon by radiation; it is also required to measure the heat capacity using laser modulation calorimetry as the laser absorptivity. 8,9) Therefore, in this study, we measured the normal spectral emissivity of liquid Ni-Al alloys using the PROSPECT system.…”

Thermophysical Property Measurements of Molten Metals by Electromagnetic Levitation Technique with Satic Magnetic Field and Thermodynamic Excess Functions

“…2 元系合金Fe (Ni (13)(14) , Cu), Ni Al (15) , Pd (Fe, Ni, Cu) (16) , Pt (Fe, Co, Ni, Cu), Au (Cu, Pd, Ni), Ti (Cu, Ni), Si (Fe, Ni, Ge) (17) , Cu Co (18) (27) (31) ．同図には， Kita ら (32) ，Pottlacher (33) (34) ，Ono ら (35) ( 1 ) 福山博之計測と制御，54(2015), 303 308.…”