珠光体、贝氏体、马氏体相变的形核*
Nucleation Mechanism of Pearlite, Bainite and Martensite*

作者: 刘宗昌 * , 计云萍 * , 任慧平 :内蒙古科技大学材料与冶金学院;

关键词: 过冷奥氏体珠光体贝氏体马氏体界面临界晶核热激活跃迁Supercooled Austenite Pearlite Bainite Martensite Interface Crystal Nucleus Heat Activation Transition

摘要:
研究过冷奥氏体转变产物的形核规律具有重要理论价值。采用20MnCrMo60Si2CrV等材料,奥氏体化后在不同温度进行等温处理,得珠光体、贝氏体、马氏体等产物,应用QUANTA-400型扫描电镜、JEM-2100透射电镜等观察各种相变的形核。发现:珠光体、贝氏体、马氏体均优先在奥氏体晶界处形核,下贝氏体、马氏体也在晶内形核。珠光体晶核由共析铁素体+共析渗碳体两相组成,共析共生,在700~650,珠光体临界晶核尺寸r* = 150~70 nm;临界形核功 155~292 J/mol。贝氏体在奥氏体的贫碳区形核,晶核是单相(BF),其临界尺度a* = 16.7~25 nm,临界形核功 2.7 × 102 J/mol。马氏体的临界晶核尺寸约为17~20 nm,形核功约为200~600 J/mol。表明随着温度的降低,临界晶核尺寸越来越小,而形核功越来越大。过冷奥氏体转变产物的形核是一个逐渐演化的过程,符合相变形核的一般规律。

Abstract:
It is significant theoretically to study the nucleation mechanism of the phase transformation products of the supercooled austenite. 20MnCrMo, 60Si2CrV and other material were respectively austenized and isothermal quenched at the different temperature to obtain pearlite, bainite and martensite. The nucleation of the phase transformation products was observed by QUANTA-400 environmental scanning electron microscope and JEM-2100 transmission electron microscope. It is found that pearlite, bainite and martensite can all nucleate at the crystal grain boundary of austenite preferentially, moreover, lower bainite and martensite can nucleate in the austenite crystal grain interior. The pearlite crystal nucleus consists of two phases of eutectoid ferrite and eutectoid cementite, which can coexist. At the temperature range of 700˚C - 650˚C, the dimension of the pearlite critical nucleus is about 150 - 70 nanometer and the critical nucleation energy is 155 - 292 J/mol. Bainite nucleates in carbon-poor region and the bainite crystal nucleus is single phase (BF). The dimension of the bainite ferrite critical nucleus is 16.7 - 25 nanometer and the critical nucleation energy is 2.7 × 102 J/mol. The dimension of the martensite critical nucleus is 17 - 20 nanometer and the critical nucleation energy is 200 - 600 J/mol. The results show that, with the decrease of the transformation temperature, the dimension of the critical nucleus is becoming smaller and smaller and the critical nucleation energy is getting larger and larger. The nucleation of the phase transformation products of the supercooled austenite is a gradual evolutionary process, which accords with the general rule of the phase transformation nucleation.

文章引用: 刘宗昌 , 计云萍 , 任慧平 (2013) 珠光体、贝氏体、马氏体相变的形核*。 材料科学, 3, 72-79. doi: 10.12677/MS.2013.32014

参考文献

[1] 刘宗昌, 任慧平著. 过冷奥氏体扩散型相变[M]. 北京: 科学出版社, 2007.

[2] 刘宗昌, 任慧平. 贝氏体与贝氏体相变[M]. 北京: 冶金工业出版社, 2009.

[3] 刘宗昌, 袁长军, 计云萍, 任慧平. 马氏体的形核及临界晶核的研究[J]. 金属热处理, 2010, 35(11): 18-22.

[4] 刘宗昌, 计云萍, 任慧平. 贝氏体铁素体的形核[J]. 材料热处理学报, 2011, 32(10): 74-79.

[5] 刘宗昌, 计云萍, 段宝玉, 任慧平. 板条状马氏体的亚结构及形成机制[J]. 材料热处理学报, 2011, 32(3): 56-62.

[6] 刘宗昌, 袁长军, 计云萍, 任慧平. 珠光体转变形核的研究[J]. 金属热处理, 2011, 36(2): 14-17.

[7] 刘宗昌, 任慧平, 王海燕. 奥氏体形成与珠光体转变[M]. 北京: 冶金工业出版社, 2010.

[8] 陈昌曙. 自然辩证法概论新编[M]. 沈阳: 东北大学出版社, 2001: 60-71.

[9] 刘宗昌. 钢件淬火开裂及防止方法(第2版)[M]. 北京: 冶金工业出版社, 2008.

[10] 刘宗昌, 王海燕, 任慧平, 李文学, 王玉峰. 贝氏体铁素体形核长大的热激活迁移机制[J]. 金属热处理, 2007, 32(11): 1-5.

[11] Z.-C. Liu, H.-Y. Wang, Y. F. Wang, W. X. Li and H.-P. Ren. Thermal activation move mechanism of bainitic ferrite nucleation and growth. Heat Treatment of Metals, 2007, 32(11): 1-5.

[12] 徐祖耀. 马氏体相变与马氏体(第2版)[M]. 北京: 科学出版社, 1999.

[13] 刘宗昌, 计云萍, 林学强, 王海燕, 任慧平. 三评马氏体相变的切变机制[J]. 金属热处理, 2010, 35(2): 118-123.

[14] 刘宗昌, 任慧平, 安胜利. 马氏体相变[M]. 北京: 科学出版社, 2012.

[15] S. A. Hackney, G. J. Shiflet. The pearlite-austenite growth interface in an Fe-0.8C-12Mn alloy. Acta Metallurgica, 1987, 35(5): 1007-1017.

[16] H. K. D. Bhadeshia. Bainite in steels (2nd Edition). London: IOM Communikations Ltd., 2001.

[17] 敖青, 秦超, 孟凡妍, 孟祥敏, 李风照. 贝氏体铁素体精细结构孪晶及纳米结构[J]. 材料热处理学报, 2002, 23(3): 20-23.

[18] Y. P. Ji, Z. C. Liu and H. P. Ren. Morphology and formation mechanism of martensite in steels with different carbon content. Advanced Materials Research, 2011, 201-203: 1612-1618.

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