Fe-M(M=Al,Nb,Si)的机械合金化研究

Study on Mechanical Alloying of Fe M(M=Al,Nb,Si)

采用Ｘ射线衍射、扫描电镜、显微硬度测试等多种分析测试手段研究了纯元素混合粉末Ｆｅ５０Ａｌ５０、Ｆｅ５０Ｎｂ５０及Ｆｅ７５Ｓｉ２５的机械合金化过程．结果表明：球磨３０ｈ后，Ｆｅ５０Ｎｂ５０转变为非晶结构，Ｆｅ７５Ｓｉ２５粉末形成具有ｂｃｃ结构的α－Ｆｅ（Ｓｉ）固溶体，Ｆｅ５０Ａｌ５０的球磨产物为α－Ｆｅ（Ａｌ）＋Ｆｅ３Ａｌ＋Ａｌ１３Ｆｅ４三组混合结构．延－延组合的Ｆｅ５０Ａｌ５０及Ｆｅ５０Ｎｂｂ２５０形成具有层片复合结构的粉末．其显微硬度在球磨初期迅速增高，延长球磨时间，增高速度减慢最后趋于稳定．而延－脆组合的Ｆｅ７５Ｓｉ２５粉末在球磨初期则形成具有弥散复合结构的粉末，其粒度变化在球磨初期与Ｆｅ５０Ａｌ５０及Ｆｅ５０Ｎｂ５０不同，无明显增大趋势．对Ｆｅ－Ｍ机械合金化的产物进行了热力学分析．

Mechanical alloying of elemental powder mixtures of Fe 50 Al 50 、Fe 50 Nb 50 and Fe 75 Si 25 is stud ied by XRD,SEM and microhardness measurement.The results reveal that powders of Fe 50 Nb 50 have been amorphized after milling for 30 h,and MA products of Fe 75 Si 25 and Fe 50 Al 50 are α Fe(Si) solid solution (bcc) and α Fe(Al)+Fe 3Al+Al 13 Fe 4 respectively.In the early period of the milling,a lamellar structure is formed during milling Fe 50 Al 50 and Fe 50 Nb 50 powders which have ductile ductile components;however,Fe 75 Si 25 powders having ductile brittle components are converted into a composite structure with dispersed Si particles in Fe powders,and its particle size is coarsened not as evidently as Fe 50 Al 50 and Fe 50 Nb 50 .Microhardness of Fe 50 Al 50 and Fe 50 Nb 50 powders increases rapidly at the early stage of the milling and,then,the increasing rate is slowed down and leveled off with the milling time.The MA products of Fe M powders are thermodynamically discussed by using Miedema's method.