According to the conventional theory of solid solutions (the nearest neighbor atomic interaction model),ordering and spinodal decomposition/clustering are mutually exclusive processes.However,it has been found that th...According to the conventional theory of solid solutions (the nearest neighbor atomic interaction model),ordering and spinodal decomposition/clustering are mutually exclusive processes.However,it has been found that the coexistence of ordering and spinodal decomposition (COSD) occurs in a large number of alloys.This fact gave a strong challenge to the conventional theory.A statistical investigation revealed that the COSD was closely related to large atomic-siae factors.It was thus proposed that the COSD stemmed from the long-range elastic interactions due to atomic-si?E disparity.In order to verify this idea,the formulism of concentration waves was applied to calculating the elastic interactions.The results proved that long-range atomic elastic interactions promoted both ordering and spinodal decomposition.A possible application of the COSD reaction was proposed,i.e.using this reaction to fabricate high-performance "natural nano-alloys".展开更多
An overview of the recently renovated high-pressure X-ray diffraction(XRD)BL10XU beamline for the diamond anvil cell at SPring-8 is presented.The renovation includes the replacement of the X-ray source and monochromat...An overview of the recently renovated high-pressure X-ray diffraction(XRD)BL10XU beamline for the diamond anvil cell at SPring-8 is presented.The renovation includes the replacement of the X-ray source and monochromator,enhanced focusing systems for high-energy XRD,and recent progress in the sample environment control techniques that are available for high-pressure studies.Other simultaneous measurement techniques for combination with XRD,such as Raman scattering spectroscopy and Mossbauer spectroscopy,have been developed to obtain complementary information under extreme conditions.These advanced techniques are expected to make significant contributions to in-depth understanding of various and complicated high-pressure phenomena.The experience gained with the BL10XU beamline could help promote high-pressure research in future synchrotron radiation facilities.展开更多
The objective of this investigation is to study the influence of vanadium（5.0wt%–10.0wt%） and chromium（0–9.0wt%） on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbide...The objective of this investigation is to study the influence of vanadium（5.0wt%–10.0wt%） and chromium（0–9.0wt%） on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbides. The alloys＇ microstructural features are presented and discussed with regard to the distribution of phase elements. The structural constituents of the alloys are spheroidal VC, proeutectoid cementite, ledeburite eutectic, rosette-shaped carbide eutectic（based on M7C3）, pearlite, martensite, and austenite. Their combinations and area fraction（AF） ratios are reported to be influenced by the alloys＇ chemical composition. Spheroidized VC particles are found to be sites for the nucleation of carbide eutectics. Cr and V are shown to substitute each other in the VC and M7C3 carbides, respectively. Chromium alloying leads to the formation of a eutectic（γ-Fe ＋ М7С3）, preventing the appearance of proeutectoid cementite in the structure. Vanadium and chromium are revealed to increase the total carbide fraction and the amount of austenite in the matrix. Cr is observed to play a key role in controlling the metallic matrix microstructure.展开更多
The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5V-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%B.The aim of this work was to study the effect of boron on the structural state of the a...The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5V-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%B.The aim of this work was to study the effect of boron on the structural state of the alloys and phase elemental distribution with respect to the formation of wear-resistant structural constituents.It was found that the alloy containing 1.6wt%B was composed of three eutectics:(a)“M_(2)(C,B)_(5)+ferrite”having a“Chinese Script”morphology(89.8vol%),(b)“M_(7)(C,B)_(3)+Austenite”having a“Rosette”morphology,and(c)“M_(3)C+Austenite”having a“Ledeburite”-shaped morphology(2.7vol%).With 2.7wt%of boron content,the bulk hardness increased from HRC 31 to HRC 38.5.The primary carboborides M_(2)(C,B)_(5) with average microhardness of HV 2797 appeared in the structure with a volume fraction of 17.6vol%.The volume fraction of eutectics(a)and(b,c)decreased to 71.2vol%and 3.9vol%,respectively.The matrix was“ferrite/austenite”for 1.6wt%B and“ferrite/pearlite”for 2.7wt%B.Both cast irons contained compact precipitates of carbide(Ti,M)C and carboboride(Ti,M)(C,В)with a volume fraction of 7.3%-7.5%.Based on the energy-dispersive X-ray spectroscopy,the elemental phase distributions and the appropriate phase formulas are presented in this work.展开更多
Full factorial design was used to evaluate the two-body abrasive resistance of 3wt%C–4wt%Mn–1.5wt%Ni spheroidal carbide cast irons with varying vanadium（5.0wt%–10.0wt%） and chromium（up to 9.0wt%） contents. The ...Full factorial design was used to evaluate the two-body abrasive resistance of 3wt%C–4wt%Mn–1.5wt%Ni spheroidal carbide cast irons with varying vanadium（5.0wt%–10.0wt%） and chromium（up to 9.0wt%） contents. The alloys were quenched at 920℃. The regression equation of wear rate as a function of V and Cr contents was proposed. This regression equation shows that the wear rate decreases with increasing V content because of the growth of spheroidal VC carbide amount. Cr influences the overall response in a complex manner both by reducing the wear rate owing to eutectic carbides（M7C3） and by increasing the wear rate though stabilizing austenite to deformation-induced martensite transformation. This transformation is recognized as an important factor in increasing the abrasive response of the alloys. By analyzing the regression equation, the optimal content ranges are found to be 7.5wt%–10.0wt% for V and 2.5wt%–4.5wt% for Cr, which corresponds to the alloys containing 9vol%–15vol% spheroidal VC carbides, 8vol%–16vol% M7C3, and a metastable austenite/martensite matrix. The wear resistance is 1.9–2.3 times that of the traditional 12wt% V–13wt% Mn spheroidal carbide cast iron.展开更多
Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed t...Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed that the simulated ED pattern of γ'-FexC(Ⅱ) model proposed by the present authors is in good agreement with experimentally observed ED pattern.It was also confirmed that the incommensurate superperiod stems from the coexistence of several γ'-Fe_xC(H) phases with different superperiods.The Fe(144)C(24)(Fe6C) model proposed by Uwakweh et al.generated ED patterns remarkably different from the experimental ones.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘According to the conventional theory of solid solutions (the nearest neighbor atomic interaction model),ordering and spinodal decomposition/clustering are mutually exclusive processes.However,it has been found that the coexistence of ordering and spinodal decomposition (COSD) occurs in a large number of alloys.This fact gave a strong challenge to the conventional theory.A statistical investigation revealed that the COSD was closely related to large atomic-siae factors.It was thus proposed that the COSD stemmed from the long-range elastic interactions due to atomic-si?E disparity.In order to verify this idea,the formulism of concentration waves was applied to calculating the elastic interactions.The results proved that long-range atomic elastic interactions promoted both ordering and spinodal decomposition.A possible application of the COSD reaction was proposed,i.e.using this reaction to fabricate high-performance "natural nano-alloys".
基金This work was partially supported by RIKEN,Japan,and MEXT/JSPS KAKENHI GrantsNos.JP24000005 and JP16H06285(to K.H.),JP26000006(to K.S.),and JP22000002 and JP15H05748(to E.O.).This work was performed under SPring-8 proposals.43 Comments from anonymous reviewers were helpful in improving the manuscript.
文摘An overview of the recently renovated high-pressure X-ray diffraction(XRD)BL10XU beamline for the diamond anvil cell at SPring-8 is presented.The renovation includes the replacement of the X-ray source and monochromator,enhanced focusing systems for high-energy XRD,and recent progress in the sample environment control techniques that are available for high-pressure studies.Other simultaneous measurement techniques for combination with XRD,such as Raman scattering spectroscopy and Mossbauer spectroscopy,have been developed to obtain complementary information under extreme conditions.These advanced techniques are expected to make significant contributions to in-depth understanding of various and complicated high-pressure phenomena.The experience gained with the BL10XU beamline could help promote high-pressure research in future synchrotron radiation facilities.
基金the Muroran Institute of Technology for funding this project
文摘The objective of this investigation is to study the influence of vanadium（5.0wt%–10.0wt%） and chromium（0–9.0wt%） on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbides. The alloys＇ microstructural features are presented and discussed with regard to the distribution of phase elements. The structural constituents of the alloys are spheroidal VC, proeutectoid cementite, ledeburite eutectic, rosette-shaped carbide eutectic（based on M7C3）, pearlite, martensite, and austenite. Their combinations and area fraction（AF） ratios are reported to be influenced by the alloys＇ chemical composition. Spheroidized VC particles are found to be sites for the nucleation of carbide eutectics. Cr and V are shown to substitute each other in the VC and M7C3 carbides, respectively. Chromium alloying leads to the formation of a eutectic（γ-Fe ＋ М7С3）, preventing the appearance of proeutectoid cementite in the structure. Vanadium and chromium are revealed to increase the total carbide fraction and the amount of austenite in the matrix. Cr is observed to play a key role in controlling the metallic matrix microstructure.
基金This work was financially supported by Ministry of Edu-cation and Science of Ukraine under the project No 0119U100080.
文摘The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5V-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%B.The aim of this work was to study the effect of boron on the structural state of the alloys and phase elemental distribution with respect to the formation of wear-resistant structural constituents.It was found that the alloy containing 1.6wt%B was composed of three eutectics:(a)“M_(2)(C,B)_(5)+ferrite”having a“Chinese Script”morphology(89.8vol%),(b)“M_(7)(C,B)_(3)+Austenite”having a“Rosette”morphology,and(c)“M_(3)C+Austenite”having a“Ledeburite”-shaped morphology(2.7vol%).With 2.7wt%of boron content,the bulk hardness increased from HRC 31 to HRC 38.5.The primary carboborides M_(2)(C,B)_(5) with average microhardness of HV 2797 appeared in the structure with a volume fraction of 17.6vol%.The volume fraction of eutectics(a)and(b,c)decreased to 71.2vol%and 3.9vol%,respectively.The matrix was“ferrite/austenite”for 1.6wt%B and“ferrite/pearlite”for 2.7wt%B.Both cast irons contained compact precipitates of carbide(Ti,M)C and carboboride(Ti,M)(C,В)with a volume fraction of 7.3%-7.5%.Based on the energy-dispersive X-ray spectroscopy,the elemental phase distributions and the appropriate phase formulas are presented in this work.
文摘Full factorial design was used to evaluate the two-body abrasive resistance of 3wt%C–4wt%Mn–1.5wt%Ni spheroidal carbide cast irons with varying vanadium（5.0wt%–10.0wt%） and chromium（up to 9.0wt%） contents. The alloys were quenched at 920℃. The regression equation of wear rate as a function of V and Cr contents was proposed. This regression equation shows that the wear rate decreases with increasing V content because of the growth of spheroidal VC carbide amount. Cr influences the overall response in a complex manner both by reducing the wear rate owing to eutectic carbides（M7C3） and by increasing the wear rate though stabilizing austenite to deformation-induced martensite transformation. This transformation is recognized as an important factor in increasing the abrasive response of the alloys. By analyzing the regression equation, the optimal content ranges are found to be 7.5wt%–10.0wt% for V and 2.5wt%–4.5wt% for Cr, which corresponds to the alloys containing 9vol%–15vol% spheroidal VC carbides, 8vol%–16vol% M7C3, and a metastable austenite/martensite matrix. The wear resistance is 1.9–2.3 times that of the traditional 12wt% V–13wt% Mn spheroidal carbide cast iron.
文摘Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed that the simulated ED pattern of γ'-FexC(Ⅱ) model proposed by the present authors is in good agreement with experimentally observed ED pattern.It was also confirmed that the incommensurate superperiod stems from the coexistence of several γ'-Fe_xC(H) phases with different superperiods.The Fe(144)C(24)(Fe6C) model proposed by Uwakweh et al.generated ED patterns remarkably different from the experimental ones.
