Microstructure Evolution and Compression Properties of a Directionally Solidified Ni-24.8%Nb Hypereutectic Alloy

Shuang Ming Li; Bing Lun Jiang; Heng Zhi Fu

doi:10.4028/www.scientific.net/MSF.654-656.1351

Paper Titles

Optimization of the Cooling Process of a Heavy Hydraulic Turbine Runner Band Casting in Heat Treatment
p.1335

Heterogeneous Nucleation and Grain Formation on Spherical and Flat Substrates
p.1339

Researches on the Nucleation Behaviors of NH4Cl Crystal on Coarse Aluminum Surfaces
p.1343

Directional Solidification and Characterization of Al₂O₃/Er₃Al₅O₁₂ Eutectic In Situ Composite by Laser Zone Remelting
p.1347

Microstructure Evolution and Compression Properties of a Directionally Solidified Ni-24.8%Nb Hypereutectic Alloy
p.1351

The Contribution of Diffusion Coefficient to the Eutectic Instability and Amorphous Phase Formation
p.1355

Analysis of an Equiaxed Dendrite Growth Model with Comparisons to In-Situ Results of Equiaxed Dendritic Growth in an Al-Ge Alloy
p.1359

Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys
p.1363

The Influence of External Mechanical Stresses on Agglomeration and Bending of Solidifying Crystals
p.1367

HomeMaterials Science ForumMaterials Science Forum Vols. 654-656Microstructure Evolution and Compression...

Microstructure Evolution and Compression Properties of a Directionally Solidified Ni-24.8%Nb Hypereutectic Alloy

Abstract:

At normal solidification conditions, in-situ composites of a Ni-24.8%Nb hypereutectic alloy can be produced at growth velocities below 5μm/s, with a thermal gradient of 180K/cm, and this low productivity remarkably restricts the application of this kind of in-situ composites. In this paper, we proposed an approach that employs an abrupt growth velocity to make the in-situ composites grow stably out of the coupled zone. In-situ composites of the Ni-24.8%Nb hypereutectic alloy were obtained at a growth velocity of 100μm/s and the productivity was greatly improved. This value is in the same order magnitude imposed on the single-crystal superalloys. The compression strengths were investigated on different microstructures involving the coupled eutectics and non-coupled eutectics. The results showed that the crack distribution and extension were mainly localized in primary Ni3Nb dendrites in the non-coupled eutectics, and that in-situ composites with the entirely coupled eutectics have improved mechanical properties and different deformation behaviors.