Solidification and grain refinement in Ti45Al2Mn2Nb1B

Grain refinement in beta-solidifying Ti44Al8Nb1B

“…With changing position from the left to the right in the solidification zone the volume fraction of the solid phase (beta phase before quenching), with grey contrast, is increased. It was reported that boron addition at 1 at% made beta dendrites much finer in Ti45Al2Mn2Nb1B [14]. A similar effect of boron addition was observed in Ti44Al8Nb1B but the extent in dendrite refinement is much smaller in this high Nbbearing alloy than in Ti45Al2Mn2Nb1B.…”

Development of a TiAl Alloy by Spark Plasma Sintering

“…It is well known that the incorporation of boron is an efficient solution to limit the grain growth of TiAl alloys through the precipitation of borides which anchor grain boundaries [23][24][25]. Fig.…”

A Quarter Century Journey of Boron as a Grain Refiner in TiAl Alloys

“…An EBSD analysis on the alpha grain orientation in a Ti45A12Mn2NblB Bridgman specimen revealed that the peritectic alpha grains in the interdendritic areas have no orientation relationship with beta dendrites at any side, i.e. the peritectic alpha grains are independent of any beta dendrites in terms of orientation [25]. Instead the peritectic alpha grains were found to have orientation relationship with some boride precipitates formed in the melt at the L/p interfaces as shown in fig.6.…”

“…24 Figure 6. EBSD orientation map showing the same orientation (same number) of alpha grains from different beta dendrites in a Ti45A12Mn2NblB Bridgman specimen (see [25] for details).…”

“…According to Hyman et al under near equilibrium solidification conditions TiB 2 has the blocky morphology when boron concentration is higher than the monovariant line in the liquidus projection of Ti-Al-B system [45], With reducing boron concentration the morphology changes into plates and flakes. For the same boron concentration the TiB morphology changes from plank-like to flake with increasing undercooling or cooling rate of solidification [25,46].…”