L12有序结构Ni74.5Pd2Al23.5合金超点阵内禀层错的形成机制

用ＴＥＭ研究了Ｌ１２长程有序结构Ｎｉ７４．５Ｐｄ２Ａｌ２３．５合金室温变形后的位错结构．结果表明,加Ｐｄ韧化的Ｎｉ７４．５Ｐｄ２Ａｌ２３．５合金室温变形组织中存在着大量超点阵内禀层错．这些层错是从以反相畴态分解的ａ／２〈０１１〉位错通过进一步的分解和反应转变来的．层错的形成是合金变形过程中位错交互作用的二次产物,并不成为影响Ｎｉ７４．５Ｐｄ２Ａｌ２３．５合金变形和韧性的主要因素．     

电感应再加热对低合金钢热轧组织影响的模拟

利用热模拟试验机Gleeble1500D研究了低合金钢变形后,冷却至一定温度进行电感应再加热后微观组织的变化情况.在不同冷却温度,以及淬火和正火两种热处理方式下,研究了再加热过程对微观组织的影响.结果表明:变形后再加热过程对淬火试样组织影响较大;冷却温度处于两相区时,电感应再加热过程能改善温度分布均匀性,影响铁素体相变过程和碳氮化物的析出行为,促进晶粒长大,能够有效地控制和改善淬火热处理钢材的微观组织和性能.     

Influence of stacking fault energy on formation of long period stacking ordered structures in Mg–Zn–Y–Zr alloys

The influence of alloying elements on the stacking fault energy (SFE) of Mg–Y–Zn–Zr alloys was calculated by using first-principles, and the microstructure of as-cast Mg-1.05Y-0.79Zn-0.07Zr (mole fraction, %) alloy prepared by conventional casting was investigated by SEM, TEM and HRTEM. The block-like long period stacking ordered (LPSO) phase, the lamellar LPSO phase and stacking faults were observed simultaneously and the lamellar LPSO structure and stacking faults were both formed on (0001)_α-Mg habit plane and grown or extended along [01i0]_α-Mg direction. The calculation results by the first-principles showed that the addition of Y can sharply decrease the stacking fault energy of the Mg–Zn–Y–Zr alloy, while Zn slightly increases the stacking fault energy of the alloy. The influence of stacking fault energy on the formation of LPSO was discussed. It shows that LPSO may nucleate directly through stacking faults and the lower stacking fault energy was in favor of formation of LPSO.     

Improved strength and ductility of high alloy containing Al-12Zn-3Mg-2.5Cu alloy by combining non-isothermal step rolling and cold rolling

Al-12Zn-3Mg-2.5Cu alloy was prepared using a liquid metallurgy route under the optimized conditions. A sample cut from the ingot was rolled non-isothermally from 400℃ to 100℃ in 100℃ steps, with 15% reduction in thickness; it was then cold rolled isothermally at room temperature for 85% reduction. The cold-rolled alloys were characterized by electron microscopy, hardness test, and tensile test to elucidate their structural evolution and evaluate their mechanical behavior. In the results, the cast alloy consists of α-aluminum and various intermetallic compounds. These compounds are segregated along the grain boundaries, which makes the alloy difficult to roll at room temperature. The combined effect of non-isothermal step rolling and cold rolling results in the nano/microsized compounds distributed uniformly in the matrix. The hardness is substantially increased after rolling. This increase in hardness is attributed to the ultra-fine grain size, fine-scale intermetallic compounds, and structural defects (e.g., dislocations, stacking faults, and sub-grains). The ultimate tensile strength of the rolled alloy is approximately 628 MPa with 7% ductility.     

Cu-Zn-Al合金纳米管与固体类流态

常温常压下研究Cu-Zn-Al合金表面的“类流态”现象时，发现经混合酸和浸蚀处理后的Cu-Zn-Al合金基体上生成了结构和形貌新颖的合金纳米管，其表面光滑，没有吸附物，长径比在40以上．通过透射电镜、X射线等观察分析证实“类流态”胞区的存在是合金纳米管生成的必要条件．合金中存在的大量微孪晶、堆垛层错、小角晶界等缺陷以及“类流态”胞区内原子结构的重排是合金纳米管形核的关键，“类流态”胞区固定了合金原子的悬浮键，为纳米管的生长提供了结构因素和能量．     

室温下单晶硅显微压痕表面位错组态的TEM观察

采用透射电镜 (TEM )定位观察了室温单晶硅显微压痕表面的微观信息 .发现了为数不少的位错圈、堆垛层错、扩展位错及压杆位错、位错偶等多种组态 .尽管产生的原因各异 ,但均为最终的低能稳定组态 .位错的存在和运动表明常温下单晶硅的压痕缺口附近产生塑性变形 .     

ZrO2 strengthened NiAl/Cr(Mo,Hf) composite fabricated by powder metallurgy

The ZrO2 ceramic particles strengthened NiAl/Cr(Mo,Hf) composite was fabricated from the rapidly solidified NiAl/Cr(Mo,Hf) pre-alloyed powder and the ZrO2 powder by powder metallurgy technique.Microstr...     

预变形量对Fe-19Mn和Fe-19Mn-1.5Si合金阻尼性能的影响

采用倒扭摆法评价了Fe 19Mn合金和Fe 19Mn 1.5Si合金在不同预变形量下的阻尼性能,并通过光学显微镜和X射线衍射仪分析了合金的微观组织形貌和层错几率.结果表明：预变形量小于4%时,由于Fe 19Mn和Fe 19Mn 1.5Si合金的层错数量增加而使其阻尼性能提高;预变形量在4%~10%时,Fe 19Mn合金的层错数量不断增加,但由于马氏体和层错的相互交割严重、层错和马氏体变得短小以及Shockley不全位错的脱钉运动困难,致使其阻尼性能反而下降;而由于Fe 19Mn 1.5Si中Si具有固溶强化和降低层错能的作用,合金本身的马氏体和层错较小,预变形量对其影响不大,即变形不改变Shockley不全位错的脱钉难度,故其阻尼性能继续保持稳定增长.     

Ni-Al系合金中的逆马氏体相变

采用多功能内耗仪测量室温至400 °C过程中，油淬Ni 36Al二元合金以及Ni27Al-12Fe、Ni-21.2Al-20Fe和Ni-24Al-16Fe三元合金的内耗和相对动力学模量，并采用X射线衍射仪分析了合金的相组成.结果表明：油淬Ni-36Al合金具有完全马氏体结构，油淬Ni-21.2Al-20Fe合金中含少量马氏体和大量类似Ni3Al和Ni5Al3的金属间化合物；在相同的频率和升温速率条件下，油淬Ni-21.2Al-20Fe的内耗峰最高且最窄，其内耗峰所对应的温度最低，油淬Ni-36Al的内耗峰最低且最宽，其内耗峰所对应的温度最高，并随Fe含量的增加而降低，且与其当量Al（Aleq）含量有关；内耗峰高度与单位时间内马氏体（L10）转变为奥氏体（γ）的转变量有关，而总的转变量与转变时间（峰宽）有关.     

Al-Mn-Si-X合金的再结晶行为研究

对Al-Mn-Si-X合金进行不同温度和不同时间的退火,采用金相显微镜（OM）、扫描电子显微（SEM）和电导率仪对不同状态的合金组织进行观察、能谱（EDS）分析和电导率测试,研究Al-Mn-Si-X合金的再结晶行为.结果表明：随着退火温度的升高,再结晶晶粒尺寸越来越小.Al-Mn-Si-X合金的再结晶晶粒大小主要受再结晶形核数量的影响,再结晶后期的晶粒长大现象不明显.Al-Mn-Si-X合金存在着大量细小弥散的AlMnSi/AlMnSiFe析出相,这些析出相强烈抑制了再结晶形核和再结晶后期的晶粒长大.当退火温度低时,形核激活能较大,形核率低,再结晶晶粒粗大;当退火温度高时,形核激活能较小,形核率增加,再结晶晶粒细小.     

标准热处理状态下高强耐蚀C-22HS合金的显微组织和力学性能

采用热力学计算、SEM与TEM观察、力学性能测试等手段研究了一种新型高强耐蚀合金C-22HS在标准热处理状态下的显微组织及力学性能.结果表明:标准热处理状态下C-22HS合金由大小不均匀的等轴晶组成,合金中析出相主要有聚集分布的颗粒相(Mo,Cr)6C和弥散分布的强化相Ni2(Mo,Cr).合金经标准热处理后不仅具有较高的强度,而且具有良好的塑性与冲击韧性;无论是在室温还是高温,它的屈服强度都大大高于C-22合金.     

等通道转角挤压对铝青铜合金组织及摩擦学性能的影响

对铝青铜合金(Cu-10%Al-4?)进行了等通道转角挤压(ECAE)热加工处理,研究了ECAE对合金微观组织、力学性能及摩擦学性能的影响.结果表明:ECAE热挤压后合金的晶粒显著细化,晶粒尺寸随着挤压道次的增加而逐步减小;晶粒细化导致合金的硬度与屈服强度显著增加,提高了合金抵抗塑性变形能力,减轻了磨粒对合金表面的犁削作用;ECAE热挤压细化了合金中的第二相,减小了脱落硬质颗粒压入合金表面的深度与宽度,降低了合金的磨损量,提高了合金的摩擦学性能.     

时效对形变Cu-Zr-Si合金组织及性能的影响

采用等径角挤压(ECAP)技术对Cu-0.16Zr-0.04Si合金在室温和液氮低温下进行1道次变形,随后在450 ℃下时效4 h.通过扫描电子显微镜(SEM)和X射线能谱仪(EDS)等技术,研究时效对合金变形组织的影响,分析了合金力学性能和导电性能的变化.结果表明:合金在变形及时效后,晶界处出现不均匀分布的棒状或颗粒状析出相,基体中出现弥散分布的细小点状析出相;合金的抗拉强度和导电率在变形时效处理后得到同步提高;随着时效时间的延长,合金的断裂韧性逐渐变差.     

高性能耐热铝合金管材的制备及性能

通过多层喷射沉积方法制备了300mm／150mm×500mm(外径／内径×长)耐热铝合金管坯,并对管坯的显微结构及不同加工状态材料性能进行了检测和分析．管坯显微结构细小均匀,除Al12(Fe,V)3Si外,无其它相析出．管坯经过挤压后,密度由85．9％提高到99．8％;室温强度由210MPa提高到456MPa;高温强度由111MPa提高到181MPa．挤压管旋压后,室温强度略有降低,高温强度无差别．旋压管径425℃,3h退火后,室温强度下降约5％,高温强度差别不大．实验结果表明,多层喷射沉积耐热铝合金管坯具有良好的加工性,该技术适合于制备耐热铝合金材料．     

Preparation of semi-solid aluminum alloy slurry poured through a water-cooled serpentine channel

A water-cooled serpentine channel pouring process was invented to produce semi-solid A356 aluminum alloy slurry for rheocasting, and the effects of pouring temperature and circulating cooling water flux on the microstructure of the slurry were investigated. The results show that at the pouring temperature of 640-680℃ and the circulating cooling water flux of 0.9 m3/h, the semi-solid A356 aluminum alloy slurry with spherical primary α(Al) grains can be obtained, whose shape factors are between 0.78 and 0.86 and the grain diameter can reach 48-68 μm. When the pouring temperatures are at 660-680℃, only a very thin solidified shell remains inside the serpentine channel and can be removed easily. When the serpentine channel is cooled with circulating water, the microstructure of the semi-solid slurry can be improved, and the serpentine channel is quickly cooled to room temperature after the completion of one pouring. In terms of the productivity of the special equipment, the water-cooled serpentine channel is economical and efficient.     

3003铝合金铸锭均匀化退火工艺及力学性能

为了节能减排,利用光学显微镜、扫描电镜、万能力学试验机等手段,研究分析了3003铝合金不同均匀化退火工艺后的组织演变及力学性能变化。结果表明:随均匀化退火温度的升高,对应的最佳工艺时间减少;620℃下退火5 h时的组织与610℃下退火7 h时基本相同,晶界处无偏析第二相粒子且晶内弥散分布第二相粒子;常温及高温瞬时拉伸时,620℃退火5 h的合金拉伸强度、延伸率均高于610℃退火7 h的。该研究通过升高退火温度、减少时间改善了3003合金铸锭均匀化退火工艺,最佳工艺为650℃下保温5 h。     

改进310奥氏体不锈钢长期时效后的组织与性能

借助扫描电子显微镜、透射电子显微镜以及高温、室温拉伸和硬度测试研究了实验室研发的改进310奥氏体不锈钢在700℃长期时效后的组织与性能.700℃时效1000 h后,实验钢在晶界和晶内析出了大量(Cr,Fe,Mo)23C6、(Cr,Fe)23C6、σ相和少量的χ相.析出相对实验钢的室温力学性能有明显的强化作用.强度增加,硬度升高20 Hv,同时延伸率仍保持在30%以上.高温下,析出强化效应减弱,延伸率轻微下降.通过断口表面和剖面观察发现,时效1000 h后,实验钢的高温拉伸断口为韧性断裂,未观察到裂纹和孔洞;而室温拉伸断口为脆性断裂,断口附近则观察到σ相中出现裂纹和孔洞.从σ相的脆-韧转变和实验钢基体的室温和高温强度的不同,讨论了在室温拉伸过程中产生裂纹和孔洞的原因,以及时效对室温和高温力学行为的不同影响.     

Nanoindentation response analysis of TiN-Cu coating deposited by magnetron sputtering

To investigate the change of the mechanical properties of soft metals doped PVD(Physical Vapor Deposition)coatings after the migration of soft metal to the surface, TiN-Cu coating was deposited on Si(100) by magnetron sputtering. The microstructure and mechanical properties at room temperature and after vacuum heat treatment at 300 ℃ were investigated. The results showed that the grains were clustered and the microstructure was porous for TiN-Cu coating at room temperature, while many micro-and nano-sized Cu particles were observed on the surface after vacuum heat treatment at 300 ℃. The elastic properties of the TiN-Cu coating after vacuum heat treatment at 300℃ degraded compared with that at room temperature. The hardness and elasticity modulus of TiN-Cu coating kept constant(3.7 GPa and 125.0 GPa, respectively) with the increase of nano-indentation depth, while the hardness and elasticity modulus of TiN-Cu coating after vacuum heat treatment at 300 ℃ increased gradually.     

挤压工艺对可生物降解 Mg–5Zn–1.5Y 镁合金显微组织及力学性能和腐蚀性能的影响

本研究分析了挤压温度和挤压比对 Mg–5Zn–1.5Y 合金的显微组织、硬度、压缩和腐蚀行为的影响。显微组织观察表明，铸造合金由α-Mg晶粒和Mg₃Zn₆Y和Mg₃Zn₃Y₂金属间化合物组成，主要位于α-Mg晶界上。较高温度下的挤压合金显示出较粗的晶粒微观结构，而以较高比率挤压的合金含有较细的微观结构，尽管在两种条件下都测量到具有较低金属间化合物的更多动态再结晶晶粒。较低温度 (340°C) 和较高比率 (1:11.5) 的组合条件提供了较高的抗压强度。然而，没有实现显着的硬度改善。挤压工艺可以降低铸造合金在模拟体液中的腐蚀率超过 80%，这主要是由于细化了微观结构。与挤压比相比，挤压温度对耐腐蚀性能的影响更为显着，挤压温度越高，耐腐蚀性能越高。     

Nd-Fe-B-Sn合金的显微组织及其对磁性能的影响

 用粉末冶金烧结法制备了Nd-Fe-B,Nd-Fe-B-Sn和Nd-Dy-Fe-B-Sn永磁合金,用SEM和TEM分析了合金的显微形貌及相结构,并用永磁参量测量仪和振动样品磁强计(VSM)测量了合金的磁性能.研究表明,添加在合金中的Sn元素主要分布在富钕相中,且改善了富钕相与基体相(Nd2Fe14B)的润湿性.合金的相组成仍然是Nd2Fe14B相(Φ相)、富钕相、富硼相(η相),添加锡没有导致合金中析出新相.但是,添加锡使Nd-Fe-B系合金的室温磁性受到损害,然而却使合金在较高温时的矫顽力温度系数和开路磁通不可逆损失明显减小.锡元素对合金显微组织的改善,可能是合金高温磁性能改善的根本原因.