蝶状马氏体的形貌和本质

Apparent morphology and nature of butterfly martensite

制备了3种高碳合金钢,研究蝶状马氏体的多种形态;采用光学显微镜、扫描电镜和透射电镜进行组织分析,探讨了蝶状马氏体的形貌和本质。发现单个片状马氏体形成方式有两种:普通核和伴生核。惯习面为{111}r、{225}r和{259}r的粗片状马氏体都是按照其中一种形核方式进行相变的。蝶状马氏体是通过"伴生核"相变形成,因此它是片状马氏体的一种形态,本质属于片状马氏体。"伴生核"相变所需的形核功和核长大功比"普通核"相变的低,所以,当粗大马氏体片停止形成后,可以通过在它的一侧长出分支,或者发生"伴生核"相变,形成蝶状马氏体,而继续进行转变。蝶状马氏体两个叶片之间的夹角只有30°、45°、60°、90°和135°共5种,没有孪晶角(70°32')。

Three kinds of high carbon alloy steels were made by solid carburizing, and the multi-morphology of butterfly martensite were studied by means of optical microscope, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） , and the substructure and nature of butterfly martensite was explored. The results show that a single plate of matensite can be formed by modes of multinucleation and associated nucleation. The phase transformation of coarse plate matensite, for which the habit planes are { 111 } r, 1225 } r and{259 t r, proceeds in accordance with one of the nucleation ways mentioned above. The butterfly martensite is formed by the associated nucleation transformation, thus it is a kind of plate matensite in nature. The work of nucleation and nucleus growth of plate martensite by associated nucleation transformation is smaller than that by multi-nucleation transformation. After stopping growth of a coarse plate of matensite, it may continue to carry on transformation through many branches to growth from one side of the coarse plate matensite, as well as to growth by associated nucleation transformation, forming butterfly martensite. The angles of 30°, 45°, 60°, 90° and 135° between the two wings of butterfly martensite are observed, and no twinning angle（70° 32 ＇） is found.