Optimization of Mechanical Properties of NiAl‐base Alloy by Suction Casting

Abstract

NiAl has recently received much attention as a potential structural material because of its many superior high-temperature properties. The lack of high-temperature strength and fracture toughness and ductility at room temperature, however, limit the use of NiAl alloys. [1,2] Of the various attempts to enhance the ductility and high temperature strength, ductile refractory-metals, like Cr, Mo, W, Re and V, can successfully improve the mechanical properties of brittle NiAl by particle or dispersion strengthening and fiber reinforcement. [3][4][5][6] In particular, NiAl-28Cr-6Mo eutectic alloys are regarded as the most logical choice of the multicomponent system due to their relatively high melting point, low density, good thermal conductivity and high creep resistance [7][8][9] as well as higher fracture toughness compared to many NiAlbased alloys. Hafnium (Hf) was found to be very effective in improving the elevated temperature strength of NiAl-Cr(Mo) eutectic alloy. Unfortunately, Hf addition weakened the fracture toughness and ductility at room temperature severely. [10,11] For NiAl-Cr(Mo)/Hf lamellar eutectic alloy, the feasible way to improve the ductility and strength further is to reduce interlamellar spacing and microsegregation of solute element Hf. Solidification at high cooling rate is anticipated to attain such microstructure. Suction casting, as a popular method to fabricate bulk amorphous, [12,13] can obtain bulk NiAl alloys at a relatively high cooling rate of about 50 ∼ 10 2 K/s that is higher than 10 -1 ∼ 10 -2 K/s for the conventionally cast.Almost no work has been reported about the effect of suction casting technique on NiAl-Cr(Mo) eutectic alloys so far. Hence, the microstructural evolution and mechanical properties of NiAl-28Cr-5.5Mo-0.5Hf alloy prepared by conventionally cast and suction casting were investigated. The results show that suction casting technique markedly improves the COMMUNICATIONS 256

Microstructure characterization and room temperature deformation of a rapidly solidified NiAl-based eutectic alloy containing trace Dy

“…The eutectic lamellar spacing was considerably refined after rapid solidification process. This is in agreement with the cooling rate difference between conventional cast and water-cooled copper mold method, which can obtain a relatively high cooling rate of about 50-10 2 K/s that is higher than 10 À1 -10 À2 K/s for the conventionally cast [12].…”

Microstructure and fracture toughness of Cr/Cr2Nb alloys with trace Y addition

“…However, in the present experiment, the samples were fabricated by water cooled copper hearth, the cooling rate could obtain a relatively high level of about 10 1 –10 2 K s − 1 . 25 In this case, the parameter K is no longer a constant, but can be described as 24 where P is the solutal Peclet number, θ α and θ β are the contact angles, D L is the diffusion coefficient of solute in the liquid, f is the volume fraction of α in the eutectic, Γ is the Gibbs–Thomson coefficient, m is the slope of the liquidus line and k is the equilibrium partition coefficient.…”

Influence of microstructure on the application of Ni-Mn-In Heusler compounds for multicaloric cooling using magnetic field and uniaxial stress

“…For that purpose, we selected the Ni-Mn-In Heusler system synthesized by suction casting. While Ni-Mn-In is one of the most promising candidates for multicaloric cooling due to its strong magnetostructural coupling, suction casting provides a facilitated synthesis of common rod-or plate-geometries with good mechanical properties [26][27][28]. Our results show that the microstructural design has a significant impact on the application of Ni-Mn-based Heusler compounds for multicaloric cooling.…”