Heterogeneous nucleation of α-Al primary crystal on L1₂modified Al_2.7Ni_0.3Ti phase

Abstract

The heterogeneous nucleation of α-Al primary crystal on the L1 2 modified Al 2.7 Ni 0.3 Ti (Al 67 Ni 8 Ti 25 ) phase was investigated. To study the effectiveness of heterogeneous nucleation by the L1 2 modified Al 2.7 Ni 0.3 Ti phase, an Al-10 vol % Al 2.7 Ni 0.3 Ti refiner was fabricated by spark plasma sintering (SPS). It was found that the maximum grain refinement performance can be achieved by the Al-10 vol % Al 2.7 Ni 0.3 Ti refiner after a holding time of 690 s. The mechanical properties of pure Al casts were improved by using the Al-10 vol % Al 2.7 Ni 0.3 Ti refiner through grain refinement. However, the grain refinement performance is relatively weaker than expected. This is because the Al-10 vol % Al 2.7 Ni 0.3 Ti refiner does not have a high thermal stability.

Review, Role of L12 Modified (Al1−xMex)3Ti Intermetallic Compounds on Heterogeneous Nucleation of Alpha Aluminum Grains

“…Therefore, it is expected that these intermetallic compounds show good grain refining performance. In our studies [13][14][15][16][17]…”

“…The minimum grain size can be achieved for the cast refined by the Al-10 vol% Al 2.7 Ni 0.3 Ti refiner after the holding time of 690 s, as shown in Fig. 9 (a) [15]. This size is about one ninth that of the unrefined cast.…”

“…where (hk) s and (hk) n are the low-index planes of the heterogeneous nucleation site and solidified phase, and [uvw] However, it is unclear why three in-plane directions are considered when evaluating the plane disregistry. Moreover, there are some possibilities to select the third axis [15]. Kato et al have proposed parameter M [20], which is approximately proportional to the specific misfit strain energy.…”

“…In eq. 3 Ti intermetallic compounds and directly prepared by gas atomization, were used [13][14][15][16][17]. Hereafter, the particles prepared by the crushing of an arc melted bulk sample and prepared by the gas atomization will be denoted as "crushed particles" and "gas-atomized particles", respectively.…”

Thermal Stability of L12‐Modified Al2.5Cu0.5Ti Particles in Al Matrix

“…In our previous studies, the influences of L1 2 -modified Al 2.7 Fe 0.3 Ti, [7,8] Al 2.75 Ni 0.25 Ti, [9] and Al 2.5 Cu 0.5 Ti [10] particles on the grain refining performance of Al have been studied. According to those studies, the L1 2modified intermetallic compound particles can act as heterogeneous nucleation sites of α-Al solidification.…”