Duplex Precipitates and Their Effects on the Room-temperature Fracture Behaviour of a NiAl-Strengthened Ferritic Alloy

A Review on Nano-Scale Precipitation in Steels

“…Again, no reduction of the uniform elongation was observed, suggesting a small increment (0.6 nm in diameter) in the size of precipitates while maintaining a high number density (in the order of 10 24 m −3 ) through nano-scale-co-precipitation can produce a large strength improvement (43% increase from 434 MPa to 622 MPa) at no expense of ductility. On the contrary, Ni3Ti [14] Cu + NiAl -4%Ni [1] Cu + NiAl -2.5%Ni [1] NiAl -3%Mn [2] NiAl -no Mn [2] NiAl [3] Cu + NiAl [15] Cu + (Ti,Mo)C [16] (Ti,Mo)C [16] TiC [29] (Ti,Mo)C [29] k carbide [7] k carbide [27] NiAl [39] (b) Figure 3. A compilation of (a) yield strength increment and (b) ductility change against precipitate size of various precipitate strengthened steels.…”

“…Different models that are based on chemical strengthening [2], modulus strengthening [2][3][4]6,33], coherency strengthening [2,6], and order strengthening [2,3] have been used to predict the interaction force between the dislocations and coherent precipitates in steels. On the other hand, models based on Orowan looping [27,39] or Asby-Orowan looping [29] are used to describe the dislocation interaction with incoherent precipitates.…”

“…The strengthening of precipitate strengthened steels relies on the pinning of dislocations, mainly through two mechanisms, the precipitate shearing mechanism [1,3,4,23,33,41] and the Orowan looping mechanism [27,29,39]. Precipitate shearing mechanism occurs when the precipitates are small in size so that dislocations can cut through (shearable or penetrable) the precipitates easily, while the Orowan looping mechanism takes place when the precipitates are large and impenetrable by dislocations [42][43][44][45][46][47].…”

“…A compilation of (a) yield strength increment and (b) ductility change against precipitate number density of various precipitate strengthened steels. TiC [40] Ni3Ti [14] Cu + NiAl -4%Ni [1] Cu + NiAl -2.5%Ni [1] NiAl -3%Mn [2] NiAl -no Mn [2] NiAl [3] Cu + NiAl [15] Cu + (Ti,Mo)C [16] (Ti,Mo)C [16] Cu + M2C [17] TiC [29] (Ti,Mo)C [29] Cu [33] K carbide [26] k carbide [7] Cu -no Ni [4] Cu -0.75%Ni [4] k carbide [27] NiAl [39] (a)…”

Atom-probe study of Cu and NiAl nanoscale precipitation and interfacial segregation in a nanoparticle-strengthened steel

“…Precipitation of nanoparticles has been recognized as one of the most effective methods to increase the strength of steels, and precipitation hardening has become the foundation in the development of many grades of highstrength steels [1][2][3][4][5][6][7][8]. It is known that the degree of strengthening so obtained is highly dependent upon the precipitate microstructure, including the structure, morphology, size, and interparticle spacing of the nanoparticles [9].…”