形变热处理对Al-Zn-Mg-Cu合金板材组织与硬度的影响

研究了形变热处理(TMT:固溶—淬火—预析出—轧制)Al-7.81Zn-1.81Mg-1.62Cu合金板材中MgZn2等第二相粒子的析出形貌和数量及其对板材组织、织构和硬度的影响.结果表明,在TMT过程中形成的纳米/亚微米尺寸MgZn2粒子,在固溶处理过程中对亚晶界/晶界迁移形成了强烈的阻碍作用,但不会诱发粒子激发形核...     

固溶-时效对Al-Zn-Mg-Sc-Zr合金板材组织与性能的影响

采用力学性能、电导率测试、金相和电子显微分析技术,研究固溶-时效处理对Al-Zn-Mg-Sc-Zr铝合金板材组织与性能的影响。结果表明:Al-Zn-Mg-Sc-Zr合金板材的最佳热处理制度为(470℃,1 h,水淬)+(120℃,24 h);在此条件下,合金的抗拉强度、屈服强度、伸长率、硬度和电导率分别为587 MPa、564 MPa、8.95%、155HB和34.5%(IACS);固溶过程中,适当提高固溶温度或延长固溶时间,合金中过剩相逐渐减少,基体过饱和程度增加;时效过程中,固溶体析出η′(MgZn2)和η(MgZn2)相,随时效时间延长,晶内析出相η′粗化,晶界上平衡相也粗化,与此同时,晶界无析出带宽化;合金的高强度来源于微量Sc、Zr引起的亚晶强化、Al3(Sc,Zr)粒子和η′相的析出强化。     

Al3Ti/7075铝基复合材料固溶处理工艺研究

研究了固溶处理对制备的Al3Ti/7075铝基复合材料显微组织和力学性能的影响.结果表明:该铝基复合材料存在的第二相颗粒为MgZn2.复合材料经480℃固溶5h后,复合材料显微硬度达到最大值68.72 HV.随固溶温度升高和固溶时间的延长,第二相颗粒回溶较多,但会发生再结晶,晶粒发生长大.复合材料经T6人工时效后硬度达到83.46 HV.     

Al_3Zr析出对Al-7.81Zn-1.62Mg-1.81Cu合金组织和织构的影响

研究三级均匀化对Al-7.81Zn-1.62Mg-1.81Cu(AA7085)合金铸锭中Al3Zr粒子析出行为,以及Al3Zr粒子析出状态对轧制板材的微结构与织构的影响。结果表明:铸锭三级均匀化处理第二级的加热温度显著影响MgZn2和Al3Zr粒子的析出行为;大量析出的MgZn2平衡相粒子作为Al3Zr粒子析出的异质核心,促进了Al3Zr粒子在晶内和晶界的均匀析出,弱化轧制板材中沿β取向线分布的{112}<111>和{123}<634>织构,抑制了{001}<100>再结晶织构,降低了再结晶分数。     

含锰高强铝合金微观组织分析

利用喷射成形方法制备了Al-Zn-Mg-Cu-Mn合金,并用XRD,OP,SEM,TEM等测试方法,分析了铝合金在沉积态、挤压态和固溶态时的显微组织。研究结果表明,沉积坯主要由等轴晶构成,晶粒平均直径为22μm。沉积坯中第二相粒子主要为MgZn2和Al6Mn相,MgZn2相在晶内弥散析出,Al6Mn相主要沿晶界析出。在挤压过程中,在晶体内析出了四方晶格的CuAl2相。在随后的固溶过程中,在固溶温度达到480℃时,MgZn2相大部分都已经回溶。当固溶温度达到500℃时,出现再结晶,在挤压过程中出现的织构消除,部分Al6Mn相回溶。     

固溶时效对Cu-1.4Ni-1.2Co-0.6Si合金组织性能的影响

研究了不同固溶工艺条件对Cu-1.4Ni-1.2Co-0.6Si合金显微组织的影响,对合金固溶-时效后的显微硬度和导电率进行了分析,并采用电子衍射及透射电镜分析其显微组织。结果表明:合金铸态组织以等轴晶为主,热轧变形组织中存在许多细小析出相。热轧合金在固溶处理过程中基体变形组织发生再结晶和晶粒长大,且随着固溶温度升高,析出相固溶量增加,至975℃时,析出相粒子基本回溶到基体中。合金中的析出相与Cu-Ni-Si合金具有相同的结构和形貌,与Cu基体的位向关系为:[001]Cu//[110]p,(010)Cu//(001)p;[112]Cu//[32 4]p,(110)Cu//(2 11)p。合金最佳固溶-时效处理工艺为975℃×1.5 h+500℃×4 h时效,在此工艺条件下,合金显微硬度为232 HV,相对导电率为49%IACS。     

固溶-时效对01975Al-Zn-Mg-Sc合金板材组织性能的影响

采用拉伸力学性能、硬度、电导率测试、金相和电子显微分析技术,研究了固溶-时效处理对01975Al-Zn-Mg-Sc合金板材组织与性能的影响。结果表明:01975铝合金板材最佳固溶时效制度为470℃1 h固溶+120℃24 h时效。在此条件下,合金的抗拉强度、屈服强度、伸长率、硬度和电导率分别为532 N/mm2、496 N/mm2、15.07%、176.1HB和34.3%(IACS)。合金的高强度来源于Al3(Sc,Zr)粒子引起的亚晶强化和η'相引起析出强化。     

7075铝基复合材料多级固溶和时效处理工艺

研究了多级固溶和时效处理工艺对制备的Al3Ti/7075铝基复合材料显微组织和力学性能的影响。结果表明,经XRD衍射图谱分析,该铝基复合材料存在的第二相颗粒为MgZn2。复合材料经440℃/3h+480℃/2h处理后,其显微硬度值为110.2HV,硬度比单级固溶提高了10%。在同一固溶温度下,随着固溶时间的延长,第二相颗粒回溶较多,但是会发生晶粒长大现象。基体合金和复合材料在同一温度(120℃)下时效时,复合材料时效速度要比基体合金时效速度快,复合材料的时效峰值硬度为147.73HV。     

喷射沉积SiCp/7090Al复合材料固溶组织及力学性能

采用多层喷射共沉积技术制备了SiCp/7090Al复合材料锭坯,对其进行了热挤压变形,研究了固溶处理对复合材料显微组织及力学性能的影响.结果表明,挤压态SiCp/7090Al复合材料的基体合金中存在大量短棒状的MgZn2相及圆形的CuA12相颗粒,晶粒内部的MgZn2粒子长约200 nm,直径约60 nm;晶粒内的CuAl2相为直径40～420 nm的球形粒子,主要分布在晶界或近晶界区域.确定了最佳固溶温度为475 ℃,固溶时间为1 h.经过固溶处理后,析出相颗粒MgZn2及CuAl2粒子溶入到基体,复合材料棒材的力学性能为:σb＝610 MPa,δ＝2.0%.     

均匀化对7050铝合金板材淬火敏感性的影响

通过光学显微镜、透射电镜以及力学性能测试,研究均匀化制度对7050铝合金板材组织演变的影响。将合金固溶后在不同速率淬火,研究均匀化制度对该合金淬火敏感性的影响。结果表明:固溶后慢速率淬火过程中,平衡相η主要位于再结晶晶粒中Al3Zr粒子的相界、再结晶晶界、亚晶晶界以及亚晶中与位错交互作用的少量Al3Zr粒子上形核析出;均匀化时间较短时(室温,120℃/h升温至465℃,8h),合金中析出少量Al3Zr粒子,固溶后的试样发生完全再结晶,此时合金淬火敏感性最好,但硬度较低;延长保温时间至20h(室温,120℃/h升温至465℃,20h),试样中析出大量Al3Zr粒子,但分布不均匀,从而导致轧制固溶后的试样依然明显再结晶,合金淬火敏感性较差;采用快速升温的双级均匀化制度((室温,120℃/h升温至465℃,20h)+(475℃,8h)),Al3Zr粒子有所长大,淬火敏感性最差;采用慢速随炉升温((室温,18℃/h升温至465℃)+(475℃,8h))的双级均匀化制度,合金中将弥散析出大量细小的Al3Zr粒子,固溶后的再结晶得到有效抑制,较多η相在亚晶界上的非均匀形核析出在一定程度上增加了合金的淬火敏感性,但该制度处理的合金仍优于再结晶程度较高的快速升温双级均匀化制度的。     

Effect of oxide species and thermomechanical treatments on the strength properties of mechanically alloyed Fe-17%Cr ferritic ODS materials

The effects of several oxide species, such as Y₂0₃, Zr0₂ and MgO, and the thermomechanical treatment (TMT) after the mechanical alloying (MA) process on the strength properties of Fe-17%Cr ferritic ODS (oxide dispersion strengthening) MA materials were investigated. Y20, showed the most uniform dispersion of the finest particles among me above oxides, but the microstructural evolution during the TMT had a larger effect on the strengthening of the alloys than the fine and uniform dispersion of the Y₂O₃ particles had.     

Regulation Mechanism of Novel Thermomechanical Treatment for Microstructure and Properties of 2E12 Aluminum Alloy

采用拉伸试验与疲劳裂纹扩展试验,以及扫描电子显微分析与透射电子显微分析,研究了热机械处理对2E12铝合金的拉伸力学性能、疲劳性能以及微观组织结构的影响。采用本热机械处理可以使2E12合金同时获得优异的强度与塑性配合,其屈服强度较T3提高了28%,抗拉强度也提高了17%,同时其延伸率仍维持T3水平（16%以上）。热机械处理样品裂纹扩展速率低于T3及T6峰时效状态。热机械处理状态的合金中包含大量相互缠结的位错,并形成了位错胞状组织。新型热机械处理大幅提升合金综合性能的机制是多种复合组织结构的协同作用,包括位错亚结构、Cu/Mg溶质原子团簇及空位复合体、GPB区等     

Microstructure and properties of thermomechanically strengthened reinforcement bars: a comparative assessment of plain-carbon and low-alloy steel grades

An extensive investigation has been carried out to study structure-property characteristics and corrosion behavior in three varieties of thermomechanically treated (TMT) reinforcement bars (rebars) produced in an integrated steel plant under the Steel Authority of India Limited. Three experimental steel heats–one of plain-carbon and two of low-alloy chemistry-were chosen for the study. Of the two lowalloy heats, one was copper-bearing and the other contained both copper and chromium for improved corrosion resistance. Hot-rolled bars for each specific chemistry were subjected to in-line thermomechanical treatment, where quenching parameters were altered to achieve different yield strength levels. All the TMT rebars, regardless of chemistry and strength level, exhibited a composite microstructure consisting of ferrite-pearlite at the core and tempered martensite at the rim. Although a tendency toward formation of Widmanstätten ferrite was evident in bars of 500 and 550 MPa yield strength levels, no adverse effect on their strength and ductility was observed. From the standpoint of mechanical properties, the rebars not only conformed to minimum yield strength requirements, but also exhibited high elongation values (21 to 28%) and excellent bendability. Corrosion studies of both TMT and cold-twisted and deformed (CTD) rebars subjected to different laboratory tests indicated that corrosion resistance increased in this order: CTD, plain-carbon TMT, copper-bearing TMT, and copper/chromium-bearing TMT.     

Effect of Ca addition on microstructure of twin-roll cast AZ31 Mg alloy

A twin-roll cast (TRC) AZ31-0.7Ca alloy sheet has been subjected to thermo-mechanical treatment (TMT) followed by annealing and its microstructure was evaluated. The as-cast microstructure of TRC AZ31-0.7Ca alloy is essentially similar to that of TRC AZ31 alloy, except for the presence of Al₂Ca dispersoid particles. The presence of Al₂Ca particles imparts significant changes to the microstructure of TMT-ed TRC alloy such as the refinement of grain size and evolution of textures different from those of ingot cast and TRC AZ31 alloys.     

填料形状对Fe@Ag核壳复合粒子的电磁特性的影响

运用液相化学还原Ag技术,制备了球形和片形2种Fe@Ag核壳复合粒子.表征了这2种屏蔽填料的物相、表面形貌和化学组成,研究了其静磁性能,分析了填料的形状对复合材料的复磁导率、电导率和屏蔽效能等电磁特性的影响.结果表明:2种复合粒子均为核壳结构完整的Fe@Ag核壳复合粒子,其Ag壳层均匀且致密;球形和片形Fe@Ag核壳复合粒子均具有良好的软磁性能;与形状各向同性的屏蔽填料相比,以片形Fe@Ag核壳复合粒子为填料的电磁屏蔽复合材料的复磁导率更高,体积电阻率更低,该复合材料在电磁波频率范围为30—1500 MHz内的屏蔽效能(SE)为-51—-55 dB,优于以球形Fe@Ag核壳复合粒子为填料的电磁屏蔽复合材料.并且从理论上分析了片形Fe@Ag核壳复合粒子的电磁屏蔽复合材料对电磁波的吸收损耗更强和屏蔽效能更高的物理本质.     

Device for Urgent Bleeding Control Produced from Titanium Nickelide with Reversible Shape Memory Effect

The optimum modes of thermomechanical treatment (TMT) are determined for alloy Ti – 50.7 at.% Ni (titanium nickelide, Nitinol) used in medicine for specific functional purposes. The developed modes of TMT have been used for creating a device based on the shape memory effect (SME) and the reversible shape memory effect (RSME), i.e., a self-actuating and easily removable “Crossbill” clip for urgent control of bleeding.     

相场法模拟不同形状的硬质颗粒对两相晶粒长大的影响

采用相场方法研究了不同颗粒体积分数及尺寸条件下不同形状的硬质颗粒对两相系统晶粒长大的影响,结果表明:球形颗粒大多处于三角晶界处,片状颗粒处于晶界处且沿晶界分布.不同形状的硬质颗粒对体积占优的α相晶粒长大无明显影响,对体积分数较小的β相晶粒长大的影响主要取决于颗粒数目.颗粒数目较少时,不同形状的硬质颗粒对β相晶粒长大无明显影响;颗粒数目较多时,片状颗粒比球形颗粒对β相晶粒长大的阻碍作用强烈.颗粒体积分数越大,颗粒对晶界的钉扎作用越强,稳态时晶粒的半径越小;颗粒尺寸越大,单个颗粒对晶界的钉扎作用越强,但总的钉扎作用越弱,稳态时晶粒的半径越大.     

Niobium carbo-nitride precipitation behavior in a high nitrogen 15Cr-15Ni heat resistant austenitic stainless steel

A high nitrogen 15Cr-15Ni niobium-stabilized austenitic alloy has been produced and subjected to a special heat treatment consisting of 5 hours of solution treatment at 1270 °C followed by hot rolling, quenching and subsequent aging at temperatures of 700 °C to 800 °C. It was found that fine dispersion of nano-sized thermally stable primary Nb(C,N) precipitates had already formed in the as-cast condition. The particles were presented at all examined stages of the TMT process (as-homogenized, as-solution treated and as-aged conditions). Secondary precipitates Nb(C,N) were densely formed during subsequent aging; these precipitates had sizes of 4 nm to 5 nm. Both the primary and secondary Nb(C,N) particles showed excellent thermal stability within the temperature range of 700 °C to 800 °C. The creep properties of the studied alloy at 750 °C were superior when compared to those of commercial type 347 stainless steel.     

粉末高温合金颗粒界面及断裂研究

研究了Rene95粉末高温合金原始颗粒边界(PPB)析出相的形貌和分布状态,及其对As—HIP合金力学性能、断口形貌和微观断裂特性的影响,原始颗粒边界密集分布的析出相质点会导致颗粒间结合界面的脆化,降低塑性,断裂沿颗粒的球面进行增大析出质点的间距,可改善合金的界面结合强度,提高HIP合金的高温塑性、持久寿命,断裂变为穿颗粒进行     

颗粒增强金属基复合材料的屈服行为

运用空间轴对称弹塑性有限元方法和混合律模型，给出了应力应变分配系数与复合材料的弹性模量，屈服强度以及切线模量之间的定量关系式，并由此提出了一种新的定义颗粒增强金属基复合材料比例极限和屈服行为的方法，进而研究了颗粒形状（球体，正圆柱体以及椭球体）和材料结构参数（颗粒体积分数和颗粒根间距）对颗粒增强金属基复合材料拉伸变形行为的影响。研究表明，通过研究应力应变分析系数及其二阶导数来确定复合材料屈服行为的方法不仅适用于短纤维增强金属基复合材料，而且也适用于颗粒增强金属基复合材料。该方法可以较好地反映出颗粒形状和材料结构参数对复合材料屈服行为的影响，预测的比例极限与已发表的实验结果吻合较好。