Effect of Cooling Rate on Morphology of TiAl3 Particles in Al-4Ti Master Alloy.

Jianhua Zhao,Lu Fu,Tao Wang,Jiansheng He,Jing Chen

doi:10.3390/ma10030238

Abstract

The Al–4Ti master alloy was fabricated by aluminum (Al) and sponge titanium particle in a resistance furnace at different cooling rates. This work aims to investigate the relationship between the cooling rate and morphology of TiAl3. The microstructure and composition of master alloys at different cooling rates were characterized and analyzed by optical microscopy (OM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and SEM with energy dispersive spectroscopy (EDS). The results showed that various morphologies of TiAl3 particles in the Al–4Ti master alloy could be acquired at different cooling rates. Petal-like, blocky, and flake-like TiAl3 particles in the Al–4Ti master alloy were respectively acquired at the cooling rates of 3.36 K/s, 2.57 K/s, and 0.31 K/s. It was also found that the morphology of TiAl3 particles in the prepared master alloy changed from petal-like to blocky, then finally to flake-like, with the decrease of cooling rate. In addition, the morphology of the TiAl3 particles has no effect on the phase inversion temperature of Al–4Ti master alloy.

Highlights

IntroductionIt is important to control the grain size (which is beneficial for improving the surface quality), decrease the hot tearing tendency, and reduce the mold-filling time
Grain refinement plays a vital role in the production of aluminum (Al) alloy
It can be observed that an overall uniform dispersion of petal-like TiAl3 particulates appearing in the aluminum matrix when Al–4Ti master alloy was cooled down in the graphite mold (Figure 2a)

Summary

Introduction

It is important to control the grain size (which is beneficial for improving the surface quality), decrease the hot tearing tendency, and reduce the mold-filling time. The refined Al alloys are widely used in aerospace, national defense, and automobile industries. For this reason, projects involved in the study of grain refinement have become significant development projects [4]. The addition of Al–Ti, Al–B, Al–Ti–B, and Al–Ti–C, as well as recently developed master alloys with other third elements (e.g., Zn) [5,6,7] has become a good way to decrease the mean grain size of the inoculated metals and alloys.

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Results

Conclusion