本文選題：Fe摻雜Mn-Cu合金 + 動(dòng)態(tài)力學(xué)分析��； 參考：《上海交通大學(xué)》2015年博士論文

【摘要】：材料的異常性能總是會(huì)引起研究者的廣泛興趣,它們?cè)诟鱾�(gè)領(lǐng)域的特殊場(chǎng)合下都存在著潛在的應(yīng)用。恒模量和類橡皮行為是材料的兩種異常性能。100年前,Guillaume發(fā)現(xiàn)并研發(fā)了兩種性能不隨溫度改變的合金——恒膨脹Invar合金以及恒模量Elinvar合金,為此他于1920年獲得了諾貝爾物理學(xué)獎(jiǎng)。Weiss建立了基于兩種磁性狀態(tài)共存的物理學(xué)框架來(lái)解釋Invar效應(yīng)。隨后基于第一性原理的計(jì)算揭示了磁性態(tài)與晶格常數(shù)及模量的關(guān)聯(lián),但是至今對(duì)于模量反常的物理圖像在介觀尺度內(nèi)仍然不清楚。本文的目的就是通過(guò)實(shí)驗(yàn)與相場(chǎng)模擬來(lái)揭示模量反常的起因。類橡皮行為的機(jī)制主要是“對(duì)稱性適應(yīng)短程序”理論(SC-SRO),其主要適用于有序合金,但對(duì)于無(wú)序合金的解釋略顯牽強(qiáng)。為此,本文將對(duì)無(wú)序合金是否存在類橡皮行為和它的起因進(jìn)行相場(chǎng)動(dòng)力學(xué)模擬研究。兩種異常性能研究主要的結(jié)果描述如下：1.對(duì)于三種Fe摻雜Mn-Cu合金進(jìn)行的動(dòng)態(tài)力學(xué)分析(DMA)顯示：低濃度摻雜合金(Mn80Fe15Cu5)與高濃度摻雜合金Mn80Fe15Cu5在-150℃至150℃均呈現(xiàn)正常的模量溫度效應(yīng),即隨溫度降低模量升高,其中前者為單一或主導(dǎo)的同軸(Collinear)反鐵磁結(jié)構(gòu),后者為單一或主導(dǎo)的非同軸(Non-collinear)反鐵磁結(jié)構(gòu)；而介于中間的摻雜合金(Mn70Fe25Cu5)在0℃至200℃之間呈現(xiàn)寬溫區(qū)的反常模量溫度效應(yīng),其為一定比例的同軸反鐵磁結(jié)構(gòu)與非同軸反鐵磁結(jié)構(gòu)的組合。針對(duì)后者的相場(chǎng)動(dòng)力學(xué)模擬,提出了“動(dòng)態(tài)反鐵磁疇尺寸”效應(yīng)(DAFDS),即高自旋同軸反鐵磁疇尺寸隨溫度上升(下降)而縮小(增大),相應(yīng)的低自旋非同軸疇界隨溫度上升(下降)而增大(縮小),由于高自旋同軸反鐵磁結(jié)構(gòu)具有較低的模量,由此導(dǎo)致了反常和連續(xù)的模量-溫度效應(yīng)。在上述模擬的基礎(chǔ)上,進(jìn)一步提出了寬溫區(qū)模量反常的必要條件和充分條件：存在多種高自旋反鐵磁疇變體是模量反常的必要條件,由摻雜引入導(dǎo)致的低自旋(非同軸)反鐵磁疇界密度提高是模量反常的充分條件,由此很好地解釋了摻雜Mn-Cu合金中出現(xiàn)的模量正常和反�，F(xiàn)象。該效應(yīng)首次在介觀尺度清晰顯示出高自旋疇長(zhǎng)大和收縮的演化伴隨模量反常的物理圖像。2.通過(guò)相場(chǎng)動(dòng)力學(xué)模擬的Fe摻雜Mn-Cu合金模量隨溫度的變化,由此顯示出在單相奧氏體中無(wú)法得到寬溫度區(qū)的恒模量效應(yīng),為此本文通過(guò)復(fù)合材料設(shè)計(jì)的思想,通過(guò)設(shè)計(jì)和優(yōu)化熱處理工藝,得到了Mn70Fe25Cu5合金中β、γ相的兩相組織,由p相控制正常模量溫度效應(yīng)、而γ相控制反常模量溫度效應(yīng),由此整體樣品在-150℃至150℃的溫度區(qū)間內(nèi)模量隨溫度波動(dòng)在2%范圍內(nèi),體現(xiàn)為300K寬溫區(qū)的Elinvar效應(yīng),其遠(yuǎn)高于目前在Mn-Cu系及Mn-Fe-Cu系合金所報(bào)道的0℃-40℃的Elinvar效應(yīng)。3.使用相場(chǎng)動(dòng)力學(xué)模擬研究了[100][110]和[111]三個(gè)不同方向加載下馬氏體變體重排的動(dòng)力學(xué)過(guò)程,結(jié)果表明,[100]方向加載去孿生(detwinning)為兩個(gè)馬氏體變體所需的臨界應(yīng)力最小,[110]方向加載去孿生為一個(gè)馬氏體變體所需要的臨界應(yīng)力其次,而[111]方向加載為母相(類似于逆相變)所需的應(yīng)力最大。當(dāng)卸載時(shí),三個(gè)方向的組織回到加載前自協(xié)調(diào)的三個(gè)馬氏體。[100]和[110]方向的卸載導(dǎo)致的偽彈性來(lái)自于馬氏體變體重排,這一機(jī)制不同于通常的應(yīng)力誘發(fā)馬氏體正逆相變機(jī)制。模擬結(jié)果也顯示出不同方向應(yīng)力加載條件下組織演化特征以及細(xì)微的界面遷移過(guò)程,即為一個(gè)加載-卸載偽彈性循環(huán)中微觀組織所經(jīng)歷的演化路徑,提出了導(dǎo)致偽彈性的馬氏體變體重排機(jī)制,這一機(jī)制不同于通常的應(yīng)力誘發(fā)馬氏體正逆相變機(jī)制。4.類橡皮行為的模擬結(jié)果顯示：回復(fù)驅(qū)動(dòng)力來(lái)自于應(yīng)力推動(dòng)三個(gè)馬氏體變體中某一變體消失后所積累的應(yīng)變能；當(dāng)長(zhǎng)時(shí)間加載造成某一變體完全消失而在卸載需要重新形核時(shí),這種情況將不利于類橡皮行為。上述機(jī)制均不需要滿足SC-SRO條件,但與SC-SRO理論預(yù)測(cè)現(xiàn)象一致,故本文稱上述在加載和卸載過(guò)程中某一馬氏體變體收縮和回復(fù)的機(jī)制為類橡皮行為的本征機(jī)制。在本文的模擬中,類橡皮行為實(shí)質(zhì)是具有應(yīng)力時(shí)效下的馬氏體變體重排的偽彈性。
[Abstract]:The abnormal properties of materials always arouse the wide interest of the researchers. They have potential applications in various special fields. Constant modulus and rubber like behavior are two kinds of abnormal properties of materials.100 years ago. Guillaume discovered and developed two kinds of alloys that do not change with temperature, constant expansion Invar alloy and constant Moduli Elinvar alloy, for which he won the Nobel prize in physics in 1920,.Weiss established a physical framework based on two kinds of magnetic states to explain the Invar effect. Then, based on the calculation of the first principle, the relation between the magnetic state and the lattice constant and modulus was revealed, but the physical image of the moduli was in the mesoscopic scale. The purpose of this article is not clear. The purpose of this paper is to reveal the cause of modulus abnormality through experiment and phase field simulation. The mechanism of rubber like behavior is mainly "symmetric adaptation short program" theory (SC-SRO), which is mainly applied to ordered alloys, but it is slightly far fetched for disordered alloys. The phase field dynamics simulation of rubber behavior and its origin is studied. The main results of two abnormal performance studies are described as follows: 1. the dynamic mechanical analysis (DMA) for three kinds of Fe doped Mn-Cu alloys shows that low concentration doped alloy (Mn80Fe15Cu5) and high concentration doped alloy Mn80Fe15Cu5 present normal modes at -150 C to 150 C The temperature effect, that is, the modulus increases with the temperature, the former is a single or dominant coaxial (Collinear) antiferromagnetic structure, and the latter is a single or dominant non coaxial (Non-collinear) antiferromagnetic structure; and the intermediate doped alloy (Mn70Fe25Cu5) shows the anomalous modulus temperature effect at a wide temperature zone between 0 and 200. A fixed proportion of the coaxial antiferromagnetic structure is combined with a non coaxial antiferromagnetic structure. According to the phase field simulation of the latter, the dynamic antiferromagnetic domain size effect (DAFDS) is proposed, that is, the size of the high spin coaxial antiferromagnetic domain is reduced with the temperature rise (decrease), and the corresponding low spin non coaxial domain boundaries increase with the temperature rise (drop). Due to the low modulus of the high spin coaxial antiferromagnetic structure, it leads to the anomalous and continuous modulus temperature effect. On the basis of the above simulation, the necessary conditions and sufficient conditions for the anomalous modulus of the modulus of the wide temperature zone are further proposed: the existence of a variety of high spin antiferromagnetic domain variants is a necessary condition for the modulus abnormality. The increase in the boundary density of the low spin (non coaxial) antiferromagnetic domain is a sufficient condition for the abnormal modulus of the moduli, which is a good explanation for the normal and anomalous phenomena of the modulus of the doped Mn-Cu alloy. This effect first clearly shows the evolution of the high spin domain and contraction in the mesoscopic scale, which is associated with the physical image of the abnormal modulus of the moduli,.2. pass. The modulus of Fe doped Mn-Cu alloy with the over phase field dynamics changes with the temperature, which shows that the constant modulus effect can not be obtained in the wide temperature zone in the single-phase austenite. Therefore, by designing and optimizing the heat treatment process, the two phase structure of beta and gamma phase in the Mn70Fe25Cu5 alloy is obtained by the idea of composite material design. The P phase is controlled by the phase field. The normal modulus temperature effect, while the gamma phase controls the abnormal modulus temperature effect, thus the modulus of the whole sample fluctuates in the range of 2% in the temperature range of -150 C to 150 C, which is reflected in the Elinvar effect of the 300K wide temperature zone, which is far higher than the phase field movement of the Elinvar effect.3. reported at the Mn-Cu and Mn-Fe-Cu alloys at 0 C -40 C. The dynamic process of martensitic rearrangement under three different directions of [100][110] and [111] is studied by mechanical simulation. The results show that the critical stress required for loading the two martensite variants in the [100] direction is the smallest, and the critical stress required by the [110] direction to be a martensitic variant is followed by the [110] direction, and [111] The maximum stress required to load the direction as the parent phase (similar to the reverse phase transition) is maximum. When unloading, the three directions of the tissues return to the three martensite.[100] and [110] direction before loading. The pseudoelasticity comes from the martensitic rearrangement. This mechanism is different from the normal stress induced martensitic transformation mechanism. It also shows the microstructure evolution characteristics and fine interface migration process under different direction stress loading conditions, that is, the evolution path of microstructures in a loading and unloading pseudo elastic cycle, and the martensitic variant rearrangement mechanism that leads to pseudoelasticity is proposed. This mechanism is different from the normal stress induced martensitic reverse phase change machine. The simulation results of.4. type rubber behavior show that the response driving force is derived from the strain energy accumulated after the stress pushes a certain variant of the three martensite variant. When a long time load causes a certain variant to disappear completely and when the unloading needs to be re nucleated, this situation will be unfavorable to the type of rubber like behavior. All of these mechanisms do not need to be full. SC-SRO condition is sufficient, but it is consistent with the prediction of SC-SRO theory. Therefore, this article calls the mechanism of the contraction and recovery of a martensitic variant in loading and unloading process as the intrinsic mechanism of rubber like behavior. In this simulation, the type of rubber behavior is essentially a pseudoelasticity of martensitic variant rearrangement under stress aging.
【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG145

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