Effects of Forming Processing on Mechanical Properties of Ti-48Al-2Mn-2Nb Intermetallics

Abstract

Ti-48Al-2Mn-2Nb alloy was produced by “centrifugal spray deposition” (CSD), and then hot isostatic pressing (HIP) was employed to remove the porosity formed by CSD. The effects of CSD and HIP processing on the mechanical properties and microstructure of the TiAl alloy were investigated. The results show that the CSD and HIP processing can both improve the strength, plasticity of the TiAl alloy, and the tensile elongation values of the CSD or HIP samples are around 3%, which are better than those of as-cast TiAl alloys in room temperature. Especially, they show more excellent compressive properties at ambient temperature with a compressive ratio of 33.8% and compressive strength of 2210MPa for the CSD samples, and a compressive ratio of 37.8% and compressive strength of 2348MPa for the HIP samples. The CSD processing also improves the fracture toughness of TiAl alloy, which is much higher than that of the HIP processing, while the HIP processing seems to be beneficial the ductility and plasticity as having a duplex structure. The effects of CSD and HIP processing on microstructure and properties of TiAl alloys are discussed to understand the deformation and fracture process of the alloy.

Fatigue Crack Growth of Ti-48Al-2Mn-2Nb Intermetallics by Centrifugal Spray Deposition

“…It indicates that lamellar structure has a better resistance to fatigue crack growth than that of duplex structure, and equiaxed gamma grains. According to the authors' research works [7,9,10] on deformation and crack initiation and growth of the CSD TiAl samples, the results indicate that lamellar structure for the CSD TiAl samples has a better resistance to crack growth than duplex structure for the HIP TiAl samples, although there are some pores existed in the CSD TiAl samples. It is also clear that lamellar structure makes a contribution improve fatigue crack growth resistance.…”

“…It is believed that the new forming process, such as powder metallurgy and spray forming，can provide TiAl intermetallic with homogeneous and fine microstructure so that they could be beneficial to ductility of room temperature. The authors, Chen et al [6][7][8][9][10][11] have systematically investigated the mechanical properties and microstructure of Ti-48Al-2Mn-2Nb alloy produced by centrifugal spray deposition (CSD). The results indicated clearly that the CSD-this new forming process can improve the plasticity of TiAl intermetallic.…”

Effects of Preparation Processing on Mechanical Properties of TiAl Intermetallic

“…The advantages of CSD over more traditional metal forming processes include better chemical homogeneity and more refined microstructure than that by the traditional ingot metallurgy, lower interstitial contamination and higher density than that by powder metallurgy, and the production of perform shapes without the need for difficult thermo-mechanical working, and so on [2]. Since then, Chen et al [3][4][5][6][7] have systematically investigated the effects of CSD processing on the mechanical properties and microstructure of the Ti-48Al-2Mn-2Nb alloy produced by CSD, which shows interesting results to improve the plasticity of intermetallic. Therefore, the paper tries to compare the effects of CSD and IM processing on mechanical properties of TiAl alloy at ambient and higher temperature.…”