Anomalous softening behavior in Ti/Ni multilayers with ultra-high hardness
Anomalous softening behavior in Ti/Ni multilayers with ultra-high hardness
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DOI：
10.1016/j.msea.2014.09.019
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发表时间：
2014-11
期刊：
影响因子：
6.4
通讯作者：
J. Shi;Z. Cao;M. Wei;G. Pan;L. Xu;X. Meng
中科院分区：
文献类型：
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作者：
J. Shi;Z. Cao;M. Wei;G. Pan;L. Xu;X. Meng
利用Ti/Ni多层膜合金化制备了Ti−Ni合金薄膜，研究了调制周期（λ）对合金化和力学性能的影响。结果表明，退火后的多层膜在λ = 2.7 ~ 54 nm范围内具有超高的硬度，远远超过共溅射Ti−Ni合金膜，且在λ=5.4 nm处硬度最大。随着压痕深度的增加，除了在λ= 5.4nm处出现硬度软化外，在λ = 13.5和27 nm处还出现了硬度软化现象，并伴随着位移突变和载荷突降。pop in事件归因于应力诱发马氏体相变，马氏体相变的临界载荷随λ的减小而增大。
We utilize alloying of Ti/Ni multilayers to prepare Ti−Ni alloy films and investigate effects of modulation period (λ) on the alloying and mechanical properties. It is found that the annealed multilayers with theλof 2.7–54 nm exhibit ultra-high hardness, far exceeding co-sputtering Ti−Ni alloy films, and the maximum hardness is found atλ=5.4 nm. Attractively, another anomalous hardness softening occurs atλof 13.5 and 27 nm with increase of indentation depth besides the softening atλ=5.4 nm, which is simultaneously accompanied by the pop-in events including displacement jumps and sudden drop of load. The pop-in events are attributed to stress-induced martensitic phase transformation and the critical load for martensitic transformation increases with the decrease ofλ.