Annealing‐Induced Hardening in Ultrafine‐Grained Ni–Mo Alloys

Gubicza, Jenő; Pereira, Pedro Henrique R.; Kapoor, Garima; Huang, Yi; Sarma, V. Subramanya; Langdon, Terence G.

doi:10.1002/adem.201800184

Cited by 25 publications

(33 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Former studies [42] have shown that heat treatments performed at moderate temperatures (at the homologous temperatures 0.35-0.45 × T m , where T m is the melting point) can cause hardening in UFG and nanomaterials. In SPD-processed samples, one possible reason for this anneal hardening is the annihilation of mobile dislocations and/or their clustering, which caused a more difficult initiation of plastic deformation after the heat treatment [42][43][44]. Indeed, in our samples the dislocation density decreased during annealing and, additionally, the dislocation arrangement parameter increased (see Table 2), which suggests significant changes in the dislocation structure.…”

Section: Discussionmentioning

confidence: 75%

“…This large increase in oxygen concentration could be responsible for the three-fold increase in HV 0 . Indeed, a former study on Ti proved that when the oxygen concentration increased from 0.1 to 0.3 wt.%, the flow stress at a plastic strain of about 8% was enhanced from about 480 to 800 MPa [44]. This strain value was selected for the comparison of the flow stresses at different oxygen contents, as hardness testing causes an 8% extra plastic strain in the material.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The Influence of Severe Plastic Deformation and Subsequent Annealing on the Microstructure and Hardness of a Cu–Cr–Zr Alloy

et al. 2020

Self Cite

View full text Add to dashboard Cite

A Cu–1.1%Cr–0.04%Zr (wt.%) alloy was processed by severe plastic deformation (SPD) using the equal channel angular pressing (ECAP) technique at room temperature (RT). It was found that when the number of passes increased from one to four, the dislocation density significantly increased by 35% while the crystallite size decreased by 32%. Subsequent rolling at RT did not influence considerably the crystallite size and dislocation density. At the same time, cryorolling at liquid nitrogen temperature yielded a much higher dislocation density. All the samples contained Cr particles with an average size of 1 µm. Both the size and fraction of the Cr particles did not change during the increase in ECAP passes and the application of rolling after ECAP. The hardness of the severely deformed Cu alloy samples can be well correlated to the dislocation density using the Taylor equation. Heat treatment at 430 °C for 30 min in air caused a significant reduction in the dislocation density for all the deformed samples, while the hardness considerably increased. This apparent contradiction can be explained by the solute oxygen hardening, but the annihilation of mobile dislocations during annealing may also contribute to hardening.

show abstract

Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

The Influence of Severe Plastic Deformation and Subsequent Annealing on the Microstructure and Hardness of a Cu–Cr–Zr Alloy

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The latter phenomenon is also confirmed by the increase of LAGB fraction during annealing as revealed by EBSD experiments. 91) As it was mentioned in the previous paragraph, the hardening effect of a more clustered dislocation structure is higher which may overwhelm the softening caused by the decrease of the dislocation density. It should also be noted that the decrease of the dislocation density during annealing does not necessarily yield a decrease of the yield strength.…”

Section: Influence Of Defect Structure On Mechanical Strengthmentioning

confidence: 87%

“…For UFG Ni1.3 wt.% (Mo,Al,Fe) processed by HPT at RT, annealing to 600 K resulted in an increase of the yield strength by 19% from 970 to 1160 MPa. 91) Simultaneously, the ultimate tensile strength increased by 13% from 1140 to 1290 MPa. This hardening cannot be explained by precipitation or grain growth as the alloy remained solid solution and the grain size was the same (³180 nm) before and after the heat treatment.…”

Section: Influence Of Defect Structure On Mechanical Strengthmentioning

confidence: 95%

“…Therefore, in HPT-processed Ni8.6 wt.% (Mo,Al,Fe) alloy annealing resulted only in a 2.4% increase of the yield strength from 1367 to 1400 MPa. 91) It should be noted that the influence of an increased solute content on the effect of annealing-induced hardening is opposite in nanocrystalline Ni alloy films. For instance, in electrodeposited NiMo layers the increase in Mo content from 0.8 to 21.5 at% resulted in an enhancement of annealing-induced hardening from 20% to 125%.…”

Section: Influence Of Defect Structure On Mechanical Strengthmentioning

confidence: 99%

See 1 more Smart Citation

Lattice Defects and Their Influence on the Mechanical Properties of Bulk Materials Processed by Severe Plastic Deformation

Gubicza

2019

Mater. Trans.

Self Cite

View full text Add to dashboard Cite

Processing of metallic materials by Severe Plastic Deformation (SPD) leads to the formation of many lattice defects (e.g., vacancies, dislocations, twin faults and grain boundaries). In this paper, the characteristic features of the defect structure in SPD-processed bulk metallic materials are overviewed. The influence of the material properties, such as the melting point, stacking fault energy and solute content, as well as the SPD-processing conditions (e.g., SPD route and applied hydrostatic pressure) on the type and densities of defects is discussed in detail. In addition, the effect of lattice defects on the mechanical strength of SPD-processed materials is oveviewed.

show abstract

Annealing‐Induced Hardening in Ultrafine‐Grained and Nanocrystalline Materials

Gubicza

2019

Adv Eng Mater

Self Cite

View full text Add to dashboard Cite

Annealing of deformed metals is considered as a process necessarily leading to softening due to the annihilation of lattice defects. However, in ultrafine‐grained (UFG) and nanocrystalline materials, annealing at moderate temperatures may induce hardening. This review summarizes those effects that can result in annealing‐induced hardening (AH) in fine‐grained materials. It is noted that only those hardening phenomena are considered as AH effects that are not accompanied by the change of the phase composition and/or the grain size. Therefore, herein, strengthening caused by precipitation is not discussed. It is shown that heat treatment of nanomaterials can cause hardening due to the relaxation of grain boundaries and segregation of alloying elements to the grain boundaries as these effects hinder the occurrence of grain boundary sliding. For UFG metallic materials processed by severe plastic deformation techniques, the annihilation of mobile dislocations and the clustering of the remaining dislocations into low‐angle grain boundaries during annealing can yield hardening. It is also shown that plastic deformation after annealing can cause a restoration of the yield strength and hardness to the same level as observed before annealing. The possible reasons of this deformation‐induced softening effect are discussed in detail.

show abstract

Annealing‐Induced Hardening in Ultrafine‐Grained Ni–Mo Alloys

Cited by 25 publications

References 20 publications

The Influence of Severe Plastic Deformation and Subsequent Annealing on the Microstructure and Hardness of a Cu–Cr–Zr Alloy

The Influence of Severe Plastic Deformation and Subsequent Annealing on the Microstructure and Hardness of a Cu–Cr–Zr Alloy

Lattice Defects and Their Influence on the Mechanical Properties of Bulk Materials Processed by Severe Plastic Deformation

Annealing‐Induced Hardening in Ultrafine‐Grained and Nanocrystalline Materials

Contact Info

Product

Resources

About