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过冷奥氏体转变产物的表面浮凸 被引量:14

Surface relief of transformation products of super-cooling austenite
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摘要 研究相变产物的浮凸现象具有理论意义,一直受到重视。近年来,应用原子力显微镜、扫描隧道显微镜、扫描电镜等先进设备,不仅精确观测了马氏体、贝氏体表面浮凸,还发现珠光体表面浮凸。本文综合阐述了过冷奥氏体转变为一系列相变产物的表面浮凸现象。发现珠光体(P)贝氏体(B)、马氏体(M)的表面浮凸均为帐篷型(∧)或N型,浮凸高度一般为数十nm,有平直的坡面,马氏体浮凸也不独具N型特征。各浮雕花样均对应于其各自的组织形貌。浮凸成因复杂,也是一种热处理畸变。过冷奥氏体的相变均为一级相变,即均有体积变化,转变为珠光体、贝氏体、马氏体时,均发生体积膨胀(比容增大)。表面浮凸是过冷奥氏体在试样表面上转变的表现,新相在试样表面形成与其在内部产生所处环境不同,相变阻力不等,新相膨胀在垂直于试样表面的外向上自由度较大,铁素体、渗碳体、贝氏体铁素体、马氏体等新相均向外鼓起。因此,表面浮凸的的根源是各相比容差,相变时试样表面不均匀体积膨胀所致。表面浮凸是过冷奥氏体在试样表面上发生相变时的普遍现象,不为某一相变所独有。 It is very important to investigate the surface relief of transformation products. Recently, many works have been carried out to observe the surface relief of bainite, martensite, pearlite by atomic force microscopy (AFM) , scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). In this paper, the surface relief of transformation products of super-cooling atjstenite was studied. The resuits show the surface relief of bainite, martensite and pearlite are all tented ( ∧ ) or N (N) type, the height of surface relief are commonly about ten nanometers, and with flat slope. The surface reliefs of martensite do not have the special feature of N (N) type. The relief patterns correspond to their own microstructure, respectively. The formation mechanism of surface relief is complex mations of super-cooling austenite are all first order phase as aberrance of heat treatment. Phase transfortransformation, namely, bulk expansion occurs when transform into pearlite, bainite, or martensite. Surface reliefs indicate the super-cooling austenite transformation on the surface of specimen, the formation condition and transformation resistance for new phase is different on surface or in interior of specimen. The free limit of bulk expansion was larger in the direction perpendicularly to specimen surface, and ferrite, cementite, bainite ferrite, martensite are all expanse outward. Accordingly, the surface relief results in the heterogeneous bulk expansion of specimen surface dur- ing phase transformation, which is a commonly phenomenon during super-cooling austeuite transformation on surface of specimen, not unique to a particular phase transformation.
出处 《中国体视学与图像分析》 2009年第3期227-236,共10页 Chinese Journal of Stereology and Image Analysis
基金 内蒙古自治区高等学校科学研究项目(NJ06073)
关键词 奥氏体 珠光体 贝氏体 马氏体 表面浮凸 比容 体积膨胀 austenite pearlite bainite martensite surface relief specific volume bulk expansion
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