Study On The Microstructure And The Mechanical Of CuAlNshape Memory Alloys With Columnar Structure

The thesis was related to CuAlNishape memory alloys with columnar structure processed by the directional casting device and ohno continuous (OCC),because the columnar structure can improve capability of CuAlNishape memory alloys.The test showed that the SME of CuAlNishape memory alloys with columnar structure are better than commen casting; the mechanics capability and machining capability are improved too.To be obtained, the casting stick used a material made of metal of high-purity aluminums copper and nickel,and the technology of directional casting and heated mould continous casting-drawing wes adopted. In order to study the relation between the columnar structure and capabilities,we failed back on microstructure analysis ingredient analysis DSCanalysis mechanics capability analysis and SMEanalysis. Besides,we also analyzed the reason why capabilities can be improved.In the course of CuAlNishape memory alloys processed by the directional casting ,we need cortrol some primary parameters, including: speed of directional castings melt temperature cooling distance temperature of castings flux ofcooling water In order to get columnar structure of CuAlNishape memory alloys,we must optimize all kinds of technics parameters.The key of success for columnar structure of CuAlNishape memory alloys by heated mould continous casting-drawing lied in improving the temperature gradient of liquid-solid zone,as to the position and length of the liquid-solid zone defined.There were changes of some main factors affecting to the solidification zone:mould temperature,casting speedand cooling capability,etc.These factors were conditional and affected each other.In the process of the continuous casting,all kinds of parameters could be matched and optimized in order to obtain the good quality CuAlNishape memory alloys.After microstructure analysis DCS analysis,the two technics can obtain CuAlNishape memory alloys withcolumnar structureThe alloy processed by directional casting has obvioued crystal boundary.On the boundary,there is some impurity conglomeration.Besides that,there wasprecipitation after cooling-heated circulation;The alloys processed by heated mould continous casting-drawing has obvioued a longitudinal columnar structure with no impurity conglomeration/The photograph of SEM had a lots of toughness sockets,as same as TiNi alloys.The SME of the sample made by OCC is better than the ones made by directional casting,and it can preponderate over the single crystal CuAlNishape memory alloys.The way of heated mould continous casting-drawing can offer a choicenessway for preparation columnar structure CuAlNishape memory alloys with continous casting.