Al、Ni含量对Cu-Al-Ni形状记忆合金马氏体相变的影响

ｕ Ａｌ Ｎｉ合金是能替代传统的Ｃｕ Ｚｒ Ａｌ、Ｔｉ Ｎｉ合金作为工业用形状记忆合金 (ＳＭＡＳ)。从技术观点上看这些合金的主要优势是它们可于近 2 0 0℃温度下使用 ,在这点上优于Ｃｕ Ｚｎ Ａｌ、Ｔｉ Ｎｉ合金 ,这两种合金却限于 10 0℃。遗憾的是尽管Ｃｕ Ａｌ Ｎｉ单晶具有良好的热机械性能 ,但为了充分满足工业应用要求这类合金还必须克服某些问题。主要问题是用传统工艺方法制得多晶合金很脆 ,尽管可以通过采用新的粉末冶金工艺方法解决这些问题。最近对于工业用Ｃｕ Ａｌ Ｎｉ形状记忆合金提出新挑战 ,一种解决这些不同技术问题…     

Ni43Co7Mn41Sn9高温形状记忆合金薄带的结构和相变

采用单辊快淬法制备了名义成分为Ni₄₃Co₇Mn₄₁Sn₉的高温形状记忆合金薄带,并对其微观组织结构和马氏体相变进行了研究.结果表明,薄带发生一步热弹性马氏体相变,经高温热处理后马氏体相变温度达到160℃.制备态薄带的晶粒为微米级,大小不一,介于2—18μm之间,与块体母合金相比晶粒明显细化,且大部分晶粒沿垂直薄带表面方向生长.室温下,薄带（消除内应力后）为正方结构的非调制马氏体,马氏体变体内部由孪晶亚结构组成.热处理后薄带的相变温度有所下降,但随着热处理温度的升高基本保持不变.     

Ni52Mn24Ga24金属间化合物的单晶生长和磁性功能

研究了Ni52Mn24Ga24合金单晶在磁场作用下能产生的目前最大的磁致伸缩应变,发现了该材料的双向相变应变效应以及磁场对此的增强现象,在1.2T磁场的作用下,可逆的相变应变达4%以上,实现这一结果的关键条件是马氏体变体的择优取向。报道了获得马氏体变体的择优取向样品的单晶生长特性和后处理方法,根据前人报道的理论模型分析了实验结果,指出磁感生应变的物理机制是磁场提供的Zeeman能驱动变体间孪晶界的移动。     

快速凝固Ni48Mn33Ga19合金的加热相变组织和结构的研究

采用铜模吸铸式快速凝固法制备了非化学计量成分的Ni48Mn33Ga19合金,研究和比较了经常规冷却和吸铸式快速冷却工艺热处理后合金相变点以及组织和结构的变化规律。结果表明,加热相变过程均为两阶段相变过程;快速凝固工艺可使铸后热处理试样的相变温度接近室温;极高的冷却速率提高了组织均匀性;Ni48Mn33Ga19合金组织经热处理后由奥氏体转变成10层马氏体。     

定向凝固Ni3Al合金高温变形后的显微组织特征

利用金相,扫描电镜和透射电子显微镜研究了定向凝固Ｎｉ３Ａｌ合金高温变形后的显微组织特征。研究结果表明,当变形速率较快时,原始柱状晶晶界无明显变化,晶内无明显结构存在;当变形速率较慢,合金呈现塑变形时,变形初期柱状晶晶界呈现“锯齿状”,后期原始柱状晶界消失,代之以晶粒尺度约为１５ｍｍ的晶粒带,晶粒带中既有小角度晶界,也有大角度晶界。     

快速凝固制备La0.83Mg0.17Ni3.25Al0.15Mn0.1储氢合金的相结构和电化学性能

采用感应熔铸+退火处理(常规冷速)及快速凝固方法制备了La0.83Mg0.17Ni3.25Al0.15Mn0.1储氢合金.系统研究了快速凝固对合金的相结构、微观组织及电化学性能的影响.X射线衍射分析表明,冷却速率对合金的相组成影响不大,但对各相丰度影响明显.随着冷却速率的增加,合金中的LaNi5相(CaCu5型结构)丰度增加,LaNi3相(PuNi3型结构)丰度减少.EPMA分析表明,快速凝固方法制备的La0.83Mg0.17Ni3.25Al0.15Mn0.1储氢合金为扁平状晶粒组织.合金电极的电化学测试表明,冷却速率对合金的活化性能影响不大.随冷速的增加,合金的最大放电容量减小,合金电极的循环稳定性改善明显,铜辊线速度为15 m/s时容量保持率达到97.03%.     

Ni48Mn33Ga19合金的马氏体相变和磁性形状记忆效应

铁磁性Heusler型合金Ni2MnGa是近年来开发的新型磁控制功能材料，但其马氏体相变温度通常远远低于室温，不利于实际应用。本文研究了多晶Ni48Mn33Ga19合金的马氏体相变特征，发现该合金的马氏体相变温度已提高到室温以上。在室温下，分别测量了不同条件下制备的试样的磁场诱发应变，提出了增大材料磁致应变的有效方法。     

Cr15Mn9Cu2Ni1N不锈钢连铸坯的高温拉伸变形特性

对于Cr15Mn9Cu2Ni1N不锈钢连铸坯,热变形过程中变形局部化的发生会影响其表面质量。从连铸坯的表层及芯部制取小型试样,利用热/力模拟试验机,进行温度950℃～1150℃范围内的拉伸试验。结果发现,随变形温度升高,该钢强度降低而延伸率提高;试样在发生颈缩,即变形局部化之前,要经历均匀变形和扩散颈缩变形,两种变形均使试样变形区获得均匀的宏观变形形貌;而高温拉伸的延伸率主要由扩散颈缩阶段的变形量决定。分析表明,均匀变形阶段主要靠应变强化抑制变形局部化的发生,而扩散颈缩变形阶段应变速率强化起主导作用。随变形温度升高,尤其在温度高于1100℃时,该钢的应变速率强化效应增强,可推迟最终变形局部化的发生,从而获得较大的延伸率。     

单晶Ni52Mn24Ga24的磁感生应变和磁增强双向形状记忆效应

铁磁性Heusler合金Ni2MnGa是近年开发的磁控制功能材料,已发现该材料结合马氏体相变可以产生大磁致伸缩（磁感生应变）和磁控制形状记忆效应两种应用功能。用磁悬浮冷坩埚提拉设备沿[001]方向生长了组分为Ni52Mn24Ga24的单晶,室温时沿该单晶样品[001]方向加磁场,在该方向获是了-0.6%的大磁感生应变。当磁场方向垂直于[001]方向时,样品在[001]方向的磁感生应变值为0.5%,同时该单晶样品在室温附近还具有可由磁场增强和控制的双向形状记忆效应。无磁场作用时,降低温度。样品在发生马氏体相变时,在[001]方向产生1.2%的收缩形变,随后升高温度,反马氏体相变时样品以同样的反应量膨胀,恢复到原来的形状,显示了特有的远需外应力协助的自发的双向形状记忆效应。其温度滞后只有10℃,如果在样品[001]方向加一个偏磁场,其形状记忆的应变往往量随磁场的增强而增大,在磁场为1.2T时可达4%,而当磁场转向[001]方向时,形状记忆的应变可以改变符号,本文指出产生大磁感生应变和磁增强双向形状记忆效应的关键是马氏体变体的择优取向。     

PHASE TRANSFORMATION BEHAVIOR AND MICROSTRUCTURE OBSERVATION OF Nb-Ru HIGH TEMPERATURE SHAPE MEMORY ALLOY

The phase transformation behavior and micro structure of Nb-Ru alloys have been studied by DSC, X-ray diffraction, optical microscopy, transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). Two-step phase transformation of CsCl (β) →face-centered tetragonal (β)→ monoclinic (β") occurs during cooling from high temperature to room temperature. The lattice parameters of marten-sites of Nb-Ru alloys were found to increase with the increase of Nb content. The martensite variants exhibit triangular self-accommodating morphology, with alternating regular bands inside. The twinning relationship between the sub structural bands was found to be (101) type I mode, and this kind of twinning interface was straight, well-defined and coherent.     

HYSTERESIS OF PHASE TRANSFORMATION TEMPERATURE IN NiTi SHAPE MEMORY ALLOY

The relationship between structure and hysteresis of phase transformation temperature inNiTi shape memory alloy has been investigated by means of TEM observation,positron an-nihilation and electrical resistivity measurement.The sequence of hysteresis for the alloy agedunder different regimes was found to be:plate martensite>R-phase>tie-like martensite.The reversible displaeement of phase boundaries of these transformations is blocked by the co-herent stress field around Ti_(11)Ni_(14)phase particles.A linear relationship between S paramet-er of positron annihilation and maximum values of temperature hysteresis showed that themismatch dislocation and elastic stress field established by Ti_(11)Ni_(14)phase precipitation arethe main factor to determine the temperature hysteresis of phase transformation in NiTi shapememory alloy.     

NiTi形状记忆合金的相变温度滞后

用透射电镜、正电子湮没和电阻测量,研究了NiTi形状记忆合金的组织结构与相变滞后的关系结果表明,经不同制度时效处理的组织,其相变温度滞后大小的顺序是:片状马氏体>R相>束状马氏体。Ti_(11)Ni_(14)相质点周围的共格应力场对这些相的可逆转变起障碍作用。正电子湮没Doppler展宽能谱S参数值与试样的温度滞后值之间存在线性关系,从而确认Ti_(11)Ni_(14)相析出的错配位错密度及由此而建立的晶体中弹性应力场分布是决定NiTi合金相变温度滞后的主要因素。     

NiAl合金的高温形状记忆效应SCIEI

观察到Ｎｉ－３４．６ａｔ．－％Ａｌ薄带单程和双程形状记忆效应（ＳＭＥ），单程ＳＭＥ发生在３００℃以上并具有很好的形状恢复率（１００％）。经高温退火后合金中产生了体积分数为１６％的延性γ′－Ｎｉ_３Ａｌ沉淀相、延性和韧性有进一步改善，同时发现退火后的薄带也具有良好的单程和双程高温ＳＭＥ。结果表明富Ｎｉ的ＮｉＡｌ有可能成为新型高温形状记忆合金（ＳＭＡ）。     

SNAP-ACTION PHASE TRANSFORMATION IN TWO-WAY SHAPE MEMORY Ni-Ti ALLOY

The snap-action behavior of a Ni-Ti alloy disc which is controlled by combination of anonlinear stress field and temperature has been studied.After treatment for two-way shapememory,all shape memory strain of snap-action finishes abruptly at a certain temperaturewithin an interval of less than 1 ms.The results of resistance measurement and in-situ X-raydiffraction indicate that the snap-action strain is mainly resulted from the snap-action β R transformation.     

Ni—Ti合金中双程形状记忆速动相变的研究

利用应力对双程形状记忆合金中相变驱动力的制约作用,在Ni-Ti合金中实现了不需附加机构的速动相变和速动双程形状记忆效应。     

EFFECT OF Mn CONTENT ON KINETIC PARAMETER DURING PHASE TRANSFORMATION IN CuZnAlMnNi SHAPE MEMORY ALLOYS

ＥＦＦＥＣＴＯＦＭｎＣＯＮＴＥＮＴＯＮＫＩＮＥＴＩＣＰＡＲＡＭＥＴＥＲＤＵＲＩＮＧＰＨＡＳＥＴＲＡＮＳＦＯＲＭＡＴＩＯＮＩＮＣｕＺｎＡｌＭｎＮｉＳＨＡＰＥＭＥＭＯＲＹＡＬＬＯＹＳ￥ＧｅｎｇＧｕｉｌｉ（ＩｎｓｔｉｔｕｔｅｆｏｒＭａｔｅｒｉａｌｓＥｎｇｉ...     

定向凝固Ni3Al合金高温变形行为的研究

定向凝固（ＤＳ）Ｎｉ３Ａｌ合金在１０００至１０５０℃温区，应变速率为２．１×１０（－４）ｓ（－１）时，应变速率敏感指数ｍ大于０．３，最大延伸可达１８５％，具有超塑变形的行为待征．金相及电子显微镜观察表明：超塑变形后，原始柱状晶内有亚结构及新晶粒生成。认为ＤＳＮｉ３Ａｌ高温变形后发生了动态再结晶过程，并由此导致ＤＳＮｉ３Ａｌ合金呈现超塑现象．     

EFFECT OF QUENCHING TEMPERATURE ON SHAPE MEMORY EFFECT OF Fe 18Mn 5Si 8Cr 4Ni ALLOY

１．ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｈａｓｂｅｅｎｒｅｐｏｒｔｅｄｔｈａｔＦｅＭｎＳｉＣｒＮｉｓｈａｐｅｍｅｍｏｒｙａｌｌｏｙｓｅｘｈｉｂｉｔｎｏｔｏｎｌｙａｇｏｏｄｓｈａｐｅｍｅｍｏｒｙｅｆｆｅｃｔ（ＳＭＥ）,ｂｕｔａｌｓｏａｇｏｏｄｃｏｒｒｏｓｉｏｎｒｅｓｉｓｔａｎｃｅ〔１,２〕,ｃｏｍｐａｒｅｄｗｉｔｈＦｅＭｎＳｉａｌｌｏｙｓ．Ｆｕｒｔｈｅｒｍｏｒｅ,ｉｔｃａｎｂｅｕｓｅｄｉｎｍａｎｕｆａｃｔｕｒｉｎｇｐｉｐｅｃｏｕｐｌｉｎｇｓｂｅｃａｕｓｅｏｆｉｔｓｈｉｇｈｐｈａｓｅｔｒａｎｓｆ…     

INFLUENCE OF PROCESSING ON SHAPE MEMORY EFFECT OF Fe-Mn-Si-Ni-C-RE SHAPE MEMORY ALLOY

Effect of carbon, compound RE, quenching temperature, pre-strain and recovery temperature on shape memory effect (SME) of Fe-Mn-Si-Ni-C-RE shape memory alloy was studied by bent measurement, thermal cycle training, SEM etc. It was shown that the grains of alloys addition with compound RE became finer and SME increased evidently. SME of the alloy was weakening gradually as carbon content increased under small strain (3%). But in the condition of large strain (more than 6%), SME of the alloy whose carbon content range from 0.1% to 0.12% showed small decreasing range, especially of alloy with the addition of compound RE. Results were also indicated that SME was improved by increasing quenching temperature (>1000℃). The amount of thermal induced martensite increased and the relative shape recovery ratio could be increased to more than 40% after 3-4 times thermal training. The relative shape recovery ratio decreased evidently depending on rising of pre-strain. Furthermore, because speed of martensite transi