多相NiAl-Cr合金的微观组织和韧脆转变行为的研究  

Investigation of Microstructure and BDTT for Multiphase NiAl-Cr Alloy

作　　者：张光业[1] 张华[1] 郭建亭[2] 

机构地区：[1]湖南科技大学机电工程学院,湖南湘潭411201 [2]中国科学院金属研究所,沈阳110016

出　　处：《材料工程》2005年第11期24-27,共4页Journal of Materials Engineering

基　　金：国家自然科学基金重大项目(59895152);"863"高技术项目(863-715-005-0030)资助

摘　　要：研究了NiAl-25Cr合金微观组织和韧脆转变行为.NiAl-25Cr合金的铸态组织为β-Ni(Al,Cr),γ'-Ni3(Al,Cr)和α-Cr三相组成,挤压后沿着挤压方向共晶区被显著拉长、变直,共晶区之间并列平行排列.经挤压变形后材料为完全再结晶的细小等轴晶,晶粒大小约3～5μm.韧脆转变温度明显依赖于应变速率,应变速率提高2个数量级,韧脆转变温度(BDTT)相应提高80K.在BDTT以下,断口形貌以β/γ'解理为主,而在BDTT以上,断口形貌出现大量的裂纹,表明合金的韧脆转变后的塑性变形由相界强度所控制.The microstructure and brittle-ductile-transient （BDT） for multiphase NiAl-25Cr alloy have been investigated. The microstructure of the tested alloy as-cast includes β-Ni（Al, Cr）,γ＇-Ni3 （Al, Cr）and α-Cr phase. After hot-extruded, the microstructure consists of equiaxed primary β-NiAl with mean grain size of 3～5μm and elongated eutectic colonies along the extrusion direction. The results reveal the BDT behavior of the tested alloy is typically dependent on the parameter of strain rate and temperature. At the temperatures below BDTT, the fracture surfaces are characterized by complete debonding along the β/γ＇ interface; above BDTT, the fracture surfaces become ductile witha large amount of cracks. It is proposed that the debonding of the ductile phase β/γ＇ is arising from the poor strength of the phase boundary.

关 键 词：微观组织 韧脆转变 金属间化合物 NIAL 

分 类 号：TG113.12[金属学及工艺—物理冶金]