Effects of Microstructure on Mechanical Properties of Harmonic Structure Designed Pure Ni
Effects of Microstructure on Mechanical Properties of Harmonic Structure Designed Pure Ni
复制标题
DOI：
10.2320/matertrans.mt-m2019145
复制
发表时间：
2019-01-01
影响因子：
1.2
通讯作者：
Ameyama, Kei
中科院分区：
文献类型：
--
作者：
Nagata, Masaya;Horikawa, Naoki;Ameyama, Kei
本研究旨在探讨微观组织对谐波结构（HS）纯ni致密材料力学性能的影响。谐波结构是细晶粒（FG）和粗晶粒（CG）在空间上分布的非均质微观结构，即CG区域（“核”）嵌在FG区域（“壳”）三维连续连接网络的矩阵中。采用等离子体旋转电极机械铣削加工纯ni粉末，再进行火花等离子烧结的粉末冶金工艺制备HS纯ni样品。粉末颗粒表面的塑性变形随MM时间的增加而增大。因此，烧结后HS纯ni样品的壳分数也有所增加。研究发现，“壳”面积的大小是控制HS纯ni压坯力学性能平衡的重要参数。具有较高“壳”面积分数的HS纯Ni样品与具有低“壳”分数的HS纯Ni样品相比，具有更高的强度和近似的伸长率。此外，还讨论了应变硬化速率和应变硬化指数对HS纯ni试样变形行为的影响。
This study aimed at investigating the influence of microstructure on mechanical properties of Harmonic Structured (HS) pure-Ni compacts. The harmonic structure is a heterogeneous microstructure with a spatial distribution of fine grains (FG) and coarse grains (CG), that is, the CG areas ('Core') embedded in the matrix of three-dimensionally continuously connected network of FG areas ('Shell'). The HS pure-Ni samples were fabricated by powder metallurgy route consisting of mechanical milling (MM) of plasma rotated electrode processed pure-Ni powder and subsequent sintering by Spark Plasma Sintering. The plastic deformation at powder particle surface increases with increasing MM time. As a result, after sintering, shell fraction also increases in the HS pure-Ni samples. It was found that the fraction of a "shell" area is an important parameter controlling the balance of the mechanical properties of the HS pure-Ni compacts. The HS pure-Ni with a higher fraction of "shell" area demonstrated higher strength and approximately similar elongation as compared to the homo Ni samples and HS pure-Ni samples containing low shell fraction. Moreover, the effects of strain hardening rates and strain hardening exponents on deformation behaviour of HS pure-Ni samples were also discussed.