Research Of Heusler Phase In NiAl-Cr Alloy Containing Alloy Element

The effects of Ti、Zr、Mo、Co content on the stability and transition rule of the Heuslerphase in NiAl-Cr alloys prepared by the three different methods were studiedThe eutectic of as-cast NiAl-Cr-5Ti alloy is composed of the grey NiAl matrix and greywhite lamellar Cr phase, it exists the Heusler(Ni2AlTi) phase. There exists a lot amount of theHeusler phase at the cell boundary for NiAl-Cr alloy containing10Ti or12Ti, with theincrease of Ti content, the Heusler phase increases. After heat treatment, the microstructure ofNiAl-Cr-Ti alloy is not basically changed, with the increase of heat treatment temperature, theHeusler decreases for the NiAl-Cr alloys containing10Ti or12Ti. The composition ofNiAl-Cr-Ti alloy containing Mo element remain unchanged, but eutectic is decreased, Cr(Mo)phase is coarsened, the Heusler phase of the NiAl-Cr alloys containing10Ti or12Ti stillexists, Cr(Mo) phase, the Heusler phase and eutectic size of the suction cast alloy are refinedobviously.The microstructure of the as-cast NiAl-Cr-1Zr alloy is composed of the NiAl matrix, Crphase and a lot amount of the Heusler(Ni2AlZr) phase at the cell boundary. With the increaseof Zr content, the Heusler phase increases. The composition of NiAl-Cr-Zr alloy containingMo element remain unchanged, Mo element does not affect the stability of the Heusler phase.After heat treatment, the Heusler of NiAl-Cr(Mo)-1Zr alloy disappears, with the increase ofheat treatment temperature, the Heusler decreases for the NiAl-Cr(Mo) alloys containing2Zror3Zr.The microstructure of the as-cast NiAl-Cr-5Co-1Zr alloy is the dendrite, it is composedof the NiAl matrix, Cr phase, Heusler(Ni2AlZr) and Al14Ni3Co3phase. The discontinuousHeusler and Al14Ni3Co3phase precipitate in the intergranular region. There do not exist theHeusler phase for the as-cast NiAl-Cr-Co-1Zr alloy containing10Co or15Co, but there existAl14Ni3Co3phase. The results show that with the increase of Co content, the stability of theHeusler phase is decreased. After heat treatment, the Heusler phase in NiAl-Cr-5Co-1Zr alloydisappears all, there still exists Al14Ni3Co3phase.