Abstract：Direct laser deposition forming technology provides wider application scenarios for Ni3Al alloys, but
the tendency of thermal cracking during forming limits its application. The hot cracking problem of Ni3Al alloy laser
direct deposition forming has been studied and discussed, the crack formation mechanism is explored through
micro characterization and mechanical property test, and the solution to optimize process optimization is proposed.
The results show that Ni3Al alloy has obvious thermal cracking tendency during laser direct deposition forming,
and macro and micro intergranular cracks will occur. The enrichment of Ti and Al elements at grain boundaries
caused by dendrite segregation promotes the formation of γ/γ′ eutectic phase, which weakens grain boundary. In
the process of rapid thermal cycling, the accumulation of residual stress causes the crack to propagate along the
grain boundary. By improving the forming atmosphere and optimizing the laser process to reasonably reduce the
energy density of the laser line, the thermal cracking tendency of direct laser deposition forming of Ni3Al alloy can
be effectively overcome, and the crack-free additive manufacturing of components can be realized.
2021, Vol. 31 
