纳米晶Ta-10%W复合粉末的制备和烧结行为研究  

Preparation and Sintering Behavior of Ta-10%W Nano-crystalline Composite Powders

作　　者：陈玉柏 范景莲[2] 郭永忠 张浩 冯美兵 杨树忠 韩勇[2] 张帆 CHEN Yubai;FAN Jinglian;GUO Yongzhong;ZHANG Hao;FENG Meibing;YANG Shuzhong;HAN Yong;ZHANG Fan(Ganzhou Nonferrous Metallurgy Research Institute Co.,Ltd.,Ganzhou 341000,Jiangxi,China;State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,Hunan,China;Jiangxi Tungsten Industry Holding Group Co.,Ltd.,Nanchang 330096,Jiangxi,China;Jiujiang Nonferrous Metal Smelting Co.,Ltd.,Jiujiang 332014,Jiangxi,China;High-Tech Special Materials of Tungsten and Rare Earth of Technology Innovation Center of Jiangxi Province,Ganzhou 341000,Jiangxi,China)

机构地区：[1]赣州有色冶金研究所有限公司,江西赣州341000 [2]中南大学粉末冶金国家重点试验室,湖南长沙410083 [3]江西钨业控股集团有限公司,江西南昌330096 [4]九江有色金属冶炼有限公司,江西九江332014 [5]江西省高端特种钨与稀土新材料技术创新中心,江西赣州341000

出　　处：《中国钨业》2023年第4期54-63,共10页China Tungsten Industry

基　　金：江西省重点研发计划(20194ABC28004)。

摘　　要：本文采用氨水中和溶液共沉淀-氢还原-钠还原-气态镁脱氧的方法,制备出了纳米晶Ta-10%W复合粉末,并将该粉末体经垂熔烧结致密化制备出了显微组织均匀细小的Ta-10%W合金。研究了复合粉末在制备过程中的相转变、形貌特征以及粉末烧结体的性能和烧结致密化行为。结果表明:前驱体复合粉末为非晶结构,经氢还原后形成了(Ta,O)和W相,经钠还原后转变为Ta2H+W相;最后经气态镁脱氧后转变为Ta+W相,获得的纳米晶Ta-10%W复合粉末平均晶粒尺寸和氧含量分别为70 nm、0.27%。粉末体在2400℃经一次垂熔保温120 min,粉末烧结体的相对密度达到93.56%,显微硬度(HV)325.4,经开坯变形和二次垂熔后,相对密度达到97.92%。合金断裂以穿晶解理断裂为主,断口呈现解理台阶、放射状裂纹、河流花样以及颗粒拔出等特征。纳米晶Ta-10%W复合粉末烧结活性高,Ta和W相互固溶缩短了扩散距离,通过纳米自催化作用相互碰撞和吸引致使晶粒并合长大,显著促进了垂熔致密化过程。Nanocrystalline Ta-10%W composite powders were prepared through the synthesis strategy:ammonia neutralization co-precipitation,followed by hydrogen reduction,sodium reduction and deoxygenation by gaseous magnesium.This components of nanocrystalline composite powders were adopted to produce high-density Ta-W alloys with uniform microstructure and fine grains through vertical sintering densitification.The phase transition,microstructure morphology characteristics,properties of powder sintered body and sintering densification behavior of composite powders during the preparation process were investigated.The results showed that the precursor composite powders were converted into(Ta,O)and W phases by hydrogen reduction,and transmitted into Ta2H+W after being reduced by sodium,then transformed into Ta and W two-phase after deoxygenation by gaseous magnesium finally.The average crystallite size and oxygen content of Ta-10%W nanocrystalline composite powders reached 70 nm and 0.27%,respectively.The relative density and microhardness(HV)of powder sintered body were 93.56%and 325.4 respectively under vertical sintering at 2400℃for 120 mins.After the process of billet deformation and secondary vertical melting,the relative density was 97.92%.The main fracture of the Ta-10%W alloys were transgranular cleavage fracture,and the fracture morphology mainly included cleavage step,radial crack,river pattern and particle pullout,etc.Nanocrystalline Ta-10%W composite powder has high sintering activity.The solid solution of Ta and W shortened the diffusion distance.These interactions and adsorption of nanocrystalline induced its spontaneous fusion and further growth,which greatly promoted the densification of vertical sintering process.

关 键 词：纳米晶 复合粉末 致密化行为 

分 类 号：TF125.241[冶金工程—粉末冶金] TG175.3[冶金工程—冶金物理化学]