Brittle-to-ductile transition in multiphase NiAl alloy

Effects of Hf additions on high-temperature mechanical properties of a directionally solidified NiAl/Cr(Mo) eutectic alloy

“…The 0.2Hf alloy had a dendritic structure and the 0.5Hf alloy consisted of intercellular structure, which was possibly related to eutectic solidification reaction. As reported previously, the solidification process of Hfcontaining NiAl/Cr(Mo) alloy can be deduced as follows [17]: the NiAl and Cr(Mo) eutectic reaction occurred at about 1718 K.…”

“…Elongations were calibrated from the change in distance between two markers on the gauge surface after testing. For clarity, the BDTT in this analysis is defined as the lowest temperature for which 5% tensile ductility could be consistently achieved in the alloy [17]. Creep tests were performed in air at temperatures ranging from 1255 to 1423 K under initial stress ranges of 30-124 MPa.…”

Microstructure, brittle–ductile transition temperature and elevated temperature compressive behavior of the directionally solidified NiAl–Cr(Mo)–Hf alloy

“…At temperature above 1233 K, the alloy fractured with appreciable elongation after yielding, showing that the alloy is ductile at elevated temperature. Thus, at the strain rate of 1.04 × 10 −4 s −1 , the BDTT of the alloy was higher than 1233 K, showing about 40 K higher than that in the as-grown state [13]. The effect of strain rate on tensile ductility (plastic strain to failure) of this alloy is plotted in Fig.…”

Investigation of a directionally solidified NiAl/Cr(Mo) composite alloyed with Hf

“…So the Hf content in the NiAl matrix is increased. An increase of Hf in the NiAl matrix improves the BDTT of NiAl (solid solution effect) [26,27] and leads to loss of ductility.…”