Effect of Ni-P content on microstructure and mechanical properties of Fe-Ni-P alloy

A series of Fe-Ni-P alloys with different Ni-P contents were prepared by micro-press sintering, and the influence of the contents on the final microstructure and mechanical properties was evaluated. Sample Fe-34(Ni, P) contains the highest Ni-P content (34.18 wt.%) and its relative density reaches 98.75%, which is attributed to the introduction of an appropriate amount of liquid phase during the sintering process. The main phase of the sample is transformed from alpha to gamma phase under the gradual increment of Ni-P content. Simultaneously, a large number of phosphides that have strong inhibition on the migration and expansion of grain boundaries are precipitated on the matrix, and synergistic effect with low-temperature sintering results in partial grain refinement. The samples with high Ni-P content have a high volume of gamma phase, which makes the sample show the optimal plasticity under the maximum compressive load. And the fracture mode has also changed from brittle fracture to a mixed mode of brittle and ductile fracture. The decrease in the proportion of alpha phase has a weakening effect on the strength, but the refinement of the grain and the increase in the phosphide are the factors that increase the strength, so that the degree of manifestation varies in different Ni-P levels.

Automated summary

Fe-Ni-P alloys with different Ni-P contents were prepared by micro-press sintering. The increase in Ni-P content led to phase transformation and phosphide precipitation, resulting in changes in the mechanical properties and microstructure of the alloy.