Microstructure and martensitic transformation characteristics of gas-atomized Ti-Ni-Cu powders
Microstructure and martensitic transformation characteristics of gas-atomized Ti-Ni-Cu powders
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DOI：
10.1016/j.jallcom.2012.02.041
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发表时间：
2013-11-15
影响因子：
6.2
通讯作者：
Nam, Tae-hyun
中科院分区：
文献类型：
--
作者：
Kim, Yeon-wook;Choi, Kyu-choul;Nam, Tae-hyun
采用气体雾化法制备了Ti 50 Ni 45 Cu 5、Ti 50 Ni 40 Cu 10和Ti 50 Ni 30 Cu 20三种Ti-Ni-Cu粉末，并采用放电等离子烧结（SPS）技术制备了多孔试样。凝固态粉末的显微组织呈胞状结构。XRD分析表明，B2-819在所有合金粉末和SPS试样中都发生了一步马氏体相变。为了研究快速凝固对马氏体相变行为的影响，对雾化态粉末、烧结体和铸态锭进行了DSC测试。在快速凝固粉末中，粉末尺寸对马氏体相变温度的依赖性很小。然而，转变温度强烈地依赖于Cu含量。Ti 50 Ni 45 Cu 5、Ti 50 Ni 40 Cu 10和Ti 50 Ni 30 Cu 20粉末在25 - 150 μ m范围内的马氏体转变开始温度（M-s）为-4.9、-17.6和32.1 ℃，Ti 50 Ni 45 Cu 5、Ti 50 Ni 40 Cu 10和Ti 50 Ni 30 Cu 20粉末的奥氏体转变结束温度（A（f））为15.6，-4.4和38.3摄氏度。对于所有Ti 50 Ni 45 Cu 5、Ti 50 Ni 40 Cu 10和Ti 50 Ni 30 Cu 20合金系统，雾化粉末的Ms和A（f）远小于SPS试样和铸态铸锭的Ms和A（f）。Ti 50 Ni 45 Cu 5粉末的温度滞后（A（f）- M-s）为20 ℃，并且随着Cu含量的增加而继续降低。Ti 50 Ni 30 Cu 10粉末的温度滞后仅为7 ℃。(C)2012爱思唯尔有限公司版权所有。
Three batches of Ti-Ni-Cu powders (Ti50Ni45Cu5, Ti50Ni40Cu10 and Ti50Ni30Cu20) were prepared by gas atomization and porous specimens were fabricated by spark plasma sintering (SPS). The microstructure of as-solidified powders exhibited a cellular structure. XRD analysis showed that one-step martensitic transformation of B2-819 occurred in all alloy powders and SPS specimens. DSC measurements of as-atomized powder, sintered bulk specimens and as-cast ingots were performed in order to study the effect of rapid solidification on martensitic transformation behaviors. The dependence of powder size on martensitic transformation temperature is very small in the rapidly solidified powders. However, the transformation temperatures were strongly dependent on the Cu-content. The martensitic transformation starting temperatures (M-s) of Ti50Ni45Cu5, Ti50Ni40Cu10 and Ti50Ni30Cu20 powders ranging between 25 and 150 mu m are -4.9, -17.6 and 32.1 degrees C and the austenite transformation finishing temperatures (A(f)) of Ti50Ni45Cu5, Ti50Ni40Cu10 and Ti50Ni30Cu20 powders were 15.6, -4.4 and 38.3 degrees C respectively. The Ms and A(f) of the as-atomized powders are much smaller than those of SPS specimens and as-cast ingots for all Ti50Ni45Cu5, Ti50Ni40Cu10 and Ti50Ni30Cu20 alloy systems. The temperature hysteresis (A(f) - M-s) of Ti50Ni45Cu5 powders was 20 degrees C and continued to decrease with increasing Cu-content. The temperature hysteresis of Ti50Ni30Cu10 powders was only 7 degrees C. (C) 2012 Elsevier B.V. All rights reserved.