Synergism between coherent precipitation strengthening and FCC-HCP type transformation-induced plasticity

It is becoming a trend that many strengthening methods are applied at the same time to overcome the strength-ductility trade-off. However, the combination of precipitation strengthening and transformation-induced plasticity (TRIP) is rarely used effectively because precipitates will hinder phase transformation. In this work, the coherent precipitation strengthening of L1(2) phase and Face-Centered Cubic (FCC) -Hexagonal Close-Packed (HCP) type martensitic transformation are combined in a single alloy. With the synergistic effect of both sides, the yield strength of aged Co(52)Cr(30)Ni(12)A(l3)Ti(3) alloy is increased from 437 MPa (annealed alloy with TRIP effect only) to 715 MPa, while retaining a uniform elongation of more than 50% at room temperature. Further research shows that whether L1(2 )phase exist will directly affect its deformation mode. In the tensile process of aged Co(52)Cr(30)Ni(12)A(l3)Ti(3) alloy, the defor-mation mode of grains without L1(2) phase will change from previous stacking fault-predominant defor-mation to the final transformation-induced plasticity. For the regions where L1(2) phase exists, martensitic transformation is difficult to occur due to the blocking effect of L1(2 )on stacking fault.

Automated summary

In this study, the coherent precipitation strengthening of L1(2) phase and Face-Centered Cubic (FCC) -Hexagonal Close-Packed (HCP) type martensitic transformation were successfully combined in a single alloy, resulting in increased yield strength and uniform elongation. The presence of L1(2) phase was found to directly affect the deformation mode of the alloy.