Shape Memory Effect of As-aged Fe-14Mn-5Si-8Cr-4Ni-0.2C Alloy

The effects of aging temperature on shape memory effect, mechanical properties and microstruc-ture of Fe-14Mn-5Si-8Cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.

Nb含量对Fe-22Mn-0.4C合金层错能和力学性能的影响

研究了微合金元素Nb对Fe-22Mn-0.4C合金层错能和力学性能的影响,利用X射线峰位移法测量计算了不同Nb含量的Fe-22Mn-0.4C合金的层错几率变化.结果表明随着Nb含量的提高,合金的层错几率降低,层错能提高.同时,Fe-22Mn-0.4C合金在拉伸变形过程中,变形机制由以TRIP效应为主导机制变为以TWIP效应为主导机制.不同的变形机制使不同Nb含量合金的力学性能发生变化,并使变形后的层错几率出现不同的变化量.

铝、铜、铬合金元素对Fe-21Mn-0.4C TWIP/TRIP钢层错能和力学性能的影响

参考文献建立了Fe-Mn-C合金层错能的热力学模型,用模型计算了铝、铜、铬元素对Fe-21Mn-0.4C合金层错能的影响规律;在Fe-21Mn-0.4C合金中添加合金元素,研究其对层错能的影响。研究结果表明：铝和铜增加合金的层错能,而铬则降低合金的层错能;当层错能低于10.7 mJ/m2时,Fe-21Mn-0.4C合金相组成为γ＋ε,当层错能为10~19.02 mJ/m2时,合金的相组成为γ＋ε＋a,当层错能高于19.02 mJ/m2时,合金的相组成为单相的γ;层错能的变化和添加了合金元素铝、铜、铬的Fe-21Mn-0.4C合金性能变化没有相一致的关系,说明影响Fe-21Mn-0.4C合金力学性能的因素很多,需要进一步的研究。