Microstructure And Mechanical Properties Of Tin/zrn Nano-multilayers

Nitride nanomultilayers with high hardness have great potential in wear resistance and is widely researched. Many superhardness nanomultilayers have been designed and manufactured. Much progress has been made in the theoretical research of "superhardness effect".TiN and ZrN are good candidates of hard coatings. However, only a few experimental results were reported about TiN/ZrN nanomultilayers. And there was a controversy regarding their mechanical properties.In this paper, TiN/ZrN nanomultilayers with different individual layer thicknesses were prepared using reactive magnetron sputtering, forming a sample group matrix. Microstructure and mechanical properties were analyzed using XRD, SEM and nanoindenter. Cracking modes were discussed. The results are as follows:1. The preferential orientations of the multilayers are affected by the thickness of TiN individual layer. Preferential orientation growth gradually transfers from (111) to (200) with the thickness of TiN individual layer increased. And the thickness of ZrN individual layer shows almost no effect. The thickness of ZrN individual layer mainly affects the quality of compositional modulation structure. With ZrN individual layer thickness increased, low angle XRD patterns become dispersed and the compositional modulation structure is damaged.2. The hetero-growth mode in nano-multilayers is decided by the thickness of TiN, ZrN individual layer. TiN(X)/ZrN(1nm) nano-multilayers formed columnar structure with (200) texture and processed sharp interface; TiN(2nm)/ZrN(y) nano-multilayers formed nano-crystalline structure with (111) texture but with low quality interface.3. The mechanical properties of TiN(X)/ZrN(1nm) nano-multilayers and TiN(2nm)/ZrN(y) nano-multilayers are decided by the above growth mode. Coherent interfaces might play an role in the mechanical behavior of TiN(X)/ZrN(1nm) nano-multilayers. And the mechanical behavior of TiN(2nm)/ZrN(y) nano-multilayers is believed to be the exhibition of so-called mixture rules of two individual layers.4. Two cracking modes exit in TiN/ZrN nano-multilayers:(1) cracking perpendicular to the film surface; (2) cracking parallel to the film surface and propogates across several columnar grains. The latter is often observed in TiN modulation layers and is good for fracture toughness of multilayers.