Internal friction observation of the ɛ↔γ transformation in a Fe–Mn alloy

Zheng-Cun, Zhou

doi:10.1016/j.msea.2006.02.134

Cited by 16 publications

(13 citation statements)

References 12 publications

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“…3(b) and 4(b) small minima are noticeable in the variation of elastic modulus during both forward and reverse transformations. These minima correspond to modulus softening (soft-mode), 20) which was reported on cooling 21) and heating 22) in binary alloys as well as in FeMn-Si-based alloys. 23) However these tendencies were not observed for C-pre in Fig.…”

Section: Resultsmentioning

confidence: 67%

“…The experimental results reported on the internal friction of Fe-Mn and Fe-Mn-Si alloys by various researchers are subdivided into two categories, i.e., the internal friction measured in isothermal conditions [1][2][3][4][5][6][7]10,11,27) and the transformation-related internal friction measured in non-isothermal conditions. 8,10,11,[18][19][20][21][22][23][24]27) …”

Section: Discussionmentioning

confidence: 99%

Section: ϫ4mentioning

confidence: 99%

“…Thus, considering a value of 100 % for Bin alloy, which was taken as reference, the calculated values decreased to 72% for C-sol and to 47.8% for C-pre. This means that the relative amount of reversible e martensite designated as VRM 22) increased in the order Cpre→C-sol→Bin.The variation of the modulus during reverse transformation is ascribed to the higher modulus value of the e phase than that of the g phase. Therefore, the decreasing tendency of the variation of the modulus in the order Bin→C-sol→C-pre also indicates that the amount of thermally induced e phase decreases in this order.…”

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confidence: 99%

“…Zhou has drawn the same conclusion from the results in a binary Fe-Mn alloy: the integral of the tan F peak is proportional to the amount of thermally induced e martensite. 22) In addition to this, the interaction of the oscillated motion of Shockley partials with short range obstacles, such as solute atoms and precipitates, must also be considered in the present study.For a better evaluation, the curves during reverse transformation in Figs. 3 to 5 were isolated from the original curves and illustrated at the corresponding positions together in Fig.…”

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Effects of Nb and C in Solution and in NbC Form on the Transformation-related Internal Friction of Fe–17Mn (mass%) Alloys

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It was also found that Bin had a negligible level of internal friction in initial state but reached a value of tanFϷ0.02 after forward martensitic transformation, g→e, which was kept even after reverse transformation. On the other hand, in the case of C-sol specimen, tan F had an initial value of about 0.01 and decreased almost to zero, after the thermal cycle.By comparing Figs. 3(b), 4(b) and 5(b) it is obvious that the first two are rather similar while a third is completely different, from the point of view of the variation of elastic modulus with temperature during forward martensitic transformation. Both forward and reverse transformations in Bin and C-sol, accompanied by obvious tan F maxima, are also commonly characterized by step-like changes of elastic modulus, as shown in Figs. 3(b) and 4(b). It is generally accepted that these step-like changes are caused by higher modulus value of e phase than that of g phase. 18) During further cooling of these specimens to lower temperatures a marked decrease of elastic modulus is noticeable, which was ascribed to the paramagnetic→antiferromagnetic transition of retained austenite.19) The Néel temperature (T N ) can be estimated as the initiating point of the modulus drop, 18) which was 315 K both for Bin and C-sol. In Figs. 3(b) and 4(b) small minima are noticeable in the variation of elastic modulus during both forward and reverse transformations. These minima correspond to modulus softening (soft-mode), 20) which was reported on cooling 21) and heating 22) in binary alloys as well as in FeMn-Si-based alloys. 23)However these tendencies were not observed for C-pre in Fig. 5(b). In the case of forward g→e transformation, which is specified by the internal friction peak shown in Fig. 5(a), the modulus was lower than before. This modulus drop might be associated with the antiferromagnetic transition. However, the temperature where the modulus starts to drop is 344 K, which is slightly higher than the T N temperature (315 K) of Bin and C-sol. The T N temperature is dependent on the chemical composition of the base material, whereas it must be independent of the existence of the NbC carbides. It should be noted here that the temperature where the modulus starts to decrease is consistent with the temperature where the internal friction starts to raise, which is the onset of the g→e transformation. Therefore, the initiation of the modulus drop is considered to be due to the softmode associated with the g→e transformation, which is observed in Bin and C-sol. The soft-mode may be immediately followed by the antiferromagnetic transition, which was reported to hinder the subsequent proceeding of the g→e transformation by stabilizing the g phase. 24)Another anomaly is seen in the modulus versus temperature curve on heating, which does not show clear step-like change due to the antiferromagnetic to paramagnetic transition at T N temperature. Instead, the modulus linearly increases and then starts to decrease around the T N temperature. The abnormal temperature coefficient of...

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Section: Resultsmentioning

confidence: 67%