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Development of High-strength Nanocrystalline Ni-W Electrodeposited Alloys and Their Plastic Deformation

高强度纳米晶镍钨电沉积合金的研制及其塑性变形

基本信息

批准号：
13450298
负责人：
YAMASAKI Tohru
金额：
$ 8.51万
依托单位：
University of Hyogo (2004)Himeji Institute of Technology (2001-2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

Electrodeposition is a superior technique for producing nanocrystalline materials having grain sizes anywhere from the essentially amorphous to nanocrystalline materials for the grain sizes of about 5-50 nm in bulk form or as coatings with no post-processing requirements. In this paper, we show the nanocrystalline Ni-W alloys having both high hardness and high ductility can be produced by electrodeposition. Especially, the high-strength nanocrystalline Ni-W alloys containing about 12.3 at.% W and 20.7 at.% W with average grain sizes of about 5 nm have been obtained : their tensile strengths were attained to about 1400 MPa and 2300 MPa, respectively.On the other band, the nanocrystalline Ni-W alloys were severely embrittled during annealing treatments. After annealing at 200 ℃, the ductile-brittle transition temperature(DBTT) increased rapidly up to about 100 ℃ at the initial period of annealing and then increased gradually with increasing the annealing time. After annealing at 180 ℃ and below, the DBTT saturated below the room temperature. By using the mold clamping techniques, the forming behaviour of the alloys with their slight grain growth during annealing at the temperature of 180 ℃ and below has been observed So, we propose 3-dimensional high precision forming processing in micrometer-size range of the nanocrystalline Ni-W alloys by combining the UV-lithographic technologies and the mold clamping ones. Formation of microduplex structures consisting of the nanocrystalline Ni-W alloy and ductile metallic phase can be possible by using the UV-lithographic techniques. Tensile strength at fracture was increased up to about 20% with forming the microduplex structures.

电沉积是一种用于生产纳米晶体材料的上级技术，所述纳米晶体材料具有从基本上无定形到纳米晶体材料的任何晶粒尺寸，所述纳米晶体材料的晶粒尺寸为约5-50 nm，呈块状形式或作为没有后处理要求的涂层。本文研究了电沉积法制备高硬度、高延展性纳米晶Ni-W合金的工艺。特别是含12.3at.%左右的纳米晶Ni-W合金，W和20.7at.%结果表明，纳米晶Ni-W合金的晶粒尺寸约为5 nm，抗拉强度分别达到1400 MPa和2300 MPa，但在退火过程中，纳米晶Ni-W合金发生严重的脆化。在200 ℃退火后，韧脆转变温度（DBTT）在退火初期迅速升高至100 ℃左右，然后随着退火时间的延长而逐渐升高。在180 ℃及以下退火后，DBTT在室温以下饱和。采用合模技术，观察了纳米晶Ni-W合金在180 ℃及以下退火过程中的成形行为，观察到合金的晶粒在退火过程中有轻微的长大。因此，我们提出了将紫外光刻技术与合模技术相结合，实现纳米晶Ni-W合金微米级三维高精度成形的方法。通过紫外光刻技术可以形成由纳米晶Ni-W合金和韧性金属相组成的微双相结构。随着微双相结构的形成，断裂处的拉伸强度增加至约20%。