Among them, it is widely believed that interfacial stress plays an important role in abnormal martensitic transformation of nanostructured materials due to the high volume fraction of interfaces. Nevertheless, this viewpoint has only been brought forward in theories, which has difficulty to be verified through experiment.

In addition, stress-induced martensitic transformation has been widely observed and selleckchem investigated in past half a century [9–11]. Martensitic transformations could be found to be affected in a variety of ways of the application of stress. However, whether the martensitic transformations in nanostructured materials can be influenced by the nanoscaled stress has rarely been documented, which is of great importance VX-689 in vitro to martensitic transformation research in nanostructured materials. The above investigations are difficult to carry out owing to the fact that it is difficult to artificially impose the nanoscaled stress within nanostructured materials. Fortunately, the current studies on nanomultilayered films provide us a feasibility of artificially imposing the interfacial stress in the nanosized films. Through alternately depositing two layers with different lattice parameters, d, the two layers can bear the interfacial tensile or compressive stress under the coherent growth structure in nanomultilayered films [12, 13]. Furthermore,

the interfacial stress can be modulated by changing the modulation NVP-AUY922 manufacturer period and ratio of two layers. To this end, Fe50Ni50 alloy (at.%, face-centered cubic (fcc) structure, d is 342 pm [14] (1 pm = 10-12 m)) with typical martensitic transformation [15, 16] and V (body-centered cubic (bcc) structure, d is 302.4 pm) without allotropic transformation PAK6 are alternately deposited to synthesize FeNi/V nanomultilayered films. By altering the thickness of the V layer, different interfacial stress will be imposed on FeNi nanolayers under

the coherent growth structure and the effect of interfacial stress on martensitic transformation of the FeNi nanofilm will be investigated. Methods Materials The FeNi/V nanomultilayered films were fabricated on silicon substrates by a magnetron sputtering system. The FeNi layer was deposited from a Fe50Ni50 alloy target (at.%, 99.99%) by DC mode, and the power was set at 100 W. The V layer was sputtered from a V target (99.99%) by RF mode, and the power was set at 80 W. Both FeNi and V targets were 75 mm in diameter. The substrates were ultrasonically cleaned in acetone and alcohol before being mounted on a rotatable substrate holder in the vacuum chamber. The distance between the substrate and target was 50 mm. The base pressure was pumped down to 5.0 × 10-4 Pa before deposition. The Ar flow rate was 15 sccm. The working pressure was 0.4 Pa, and the substrate was heated up to 300°C during deposition.