Studies on the Fe-Mn-Si-Cr-RE shape memory alloys

• Main Authors: Yen-Chieh Tu, 涂延傑
• Other Authors: Kun-Ming Lin
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/79320105246142975906

碩士 === 逢甲大學 === 材料科學所 === 92 === The Fe-25Mn-6Si-5Cr-0.11RE shape memory alloy was prepared by vacuum induction melting (VIM) technique. The shape memory effect, thermo-mechanical training and related basic properties of Fe-25Mn-6Si-5Cr-0.11RE alloy were investigated by various techniques. The deformation texture of the alloy after thermo-mechanical treatment was studied by using orientation distribution function (ODF) analysis. Experimental results showed that the shape memory effect can be improved by the addition of a small amount of rare earth elements in Fe-Mn-Si-Cr alloy. The shape recovery ratio of the Fe-25Mn-6Si-5Cr-0.11RE alloy can achieve 94% under the condition of 4% pre-strain in the as-rolled state. The second phase particle formed at the grain boundaries is found in alloys after suitable heat treatment. The formation temperature of the second phase particle is within the range of 600℃ to 800℃, which will degrade the shape memory effect of the alloys. The shape recovery ratio of the alloy after the treatment at 900℃ for 30 min can almost achieve 100% after three cycles of thermo-mechanical training, with 3% strain at recovery temperature of 600℃. For thermo-mechanical training with lower recovery temperature (400℃), the alloy can also complete shape recovery after six cycles of training with 2% strain. For Fe-25Mn-6Si-5Cr-0.11RE alloy rolled with 10% strain then annealed at 500℃ for 1 hour, the main textures of the alloy shift from and at initial state to and by ODF test. The orientation density of the alloy with 10% strain hot-rolled is higher as rolled at 200℃ than that at room temperature.