高温氧化对AlN/TiC/TZP材料的组织结构与性能的影响

研究了 Ａｌ Ｎ／ Ｔｉ Ｃ／ Ｔ Ｚ Ｐ复合材料的高温氧化及其对组织与性能的影响．高温氧化实验表明,在１４００ ℃范围内,随氧化温度和时间增加,氧化增重符合抛物线规律,同时复合材料的强度和韧性急剧下降．用 Ｘ Ｒ Ｄ、 Ｓ Ｅ Ｍ 和 Ｔ Ｅ Ｍ 观察分析了氧化前后试样的显微组织结构．探讨了复合材料的高温氧化机理．     

挤压比对AZ91镁合金组织及力学性能的影响

研究了挤压比对热挤压AZ91镁合金显微组织和拉伸性能的影响.结果表明：热挤压可以显著细化AZ91镁合金的晶粒，而且随着挤压比的增加，晶粒变得更加细小；增大挤压比也可以提高AZ91镁合金在不同实验温度下的抗拉强度和屈服强度，且经过3种挤压比挤压的AZ91镁合金在150 ℃时均呈现最高的抗拉强度和屈服强度；此外，经不同挤压比挤压的AZ91镁合金的伸长率均随实验温度的升高而增加.通过拉伸断口形貌的扫描电镜分析，确定了热挤压AZ91镁合金在室温拉伸时均表现为解理断裂为主的脆性断裂，而在较高温度下拉伸时则基本呈现韧性断裂特征.     

氢蚀对Cr-Mo钢断裂韧性和裂纹行为的影响

选用经４００℃，２０ＭＰａ，１０５ｈ氢暴露后的Ｃｒ－Ｍｏ钢进行了拉伸试验、疲劳试验和断裂韧性试验。结果表明，氢蚀使Ｃｒ－Ｍｏ钢强度、塑性和断裂韧性均降低，也使断裂机制由韧窝型转变为解理脆性，氢蚀使疲劳裂纹扩展速率增加，门槛值降低。Ｃｒ－Ｍｏ钢氢蚀后，随应力比Ｒ的增加，疲劳裂纹扩展门槛值大幅度降低。     

氢蚀对Cr—Mo钢断裂韧性和裂纹行为的影响

选用经４００℃２０ＭＰａ，１０＾５ｈ氢暴露后的Ｃｒ－Ｍｏ钢进行了拉伸试验、疲劳试验和断裂韧性试验。结果表明，氢蚀使Ｃｒ－Ｍｏ钢强度、塑性和断裂韧性均降低，也使断裂机制由韧窝型转变为解理脆性，氢蚀使疲劳扩展速度增加，门榄值降低。Ｃｒ－Ｍｏ钢氢蚀后，随应力比Ｒ的增加，疲劳裂纹扩展门榄值大幅度降低。     

高温氧化对AIN／TiC／TZP材料的组织结构与性能的影响

研究了ＡＩＮ／ＴｉＣ／ＴＺＰ复合材料的高温氧化及其对组织与性能的影响。高温氧化实验表明,在１４００℃范围内,随氧化温度和时间增加,氧化增重符合抛物线规律,同时复合材料的强度和韧性急剧下降。用ＸＲＤ、ＳＥＭ和ＴＥＭ观察分析了氧化前后试样的显微组织结构。探讨了复合材料的高温氧化机理。     

Mn对Fe3Al金属间化合物不同温度下拉伸性能的影响

探讨了不同Ｍｎ含量对Ｆｅ３Ａｌ金属间化合物在２５～８００℃下拉伸性能的影响；并就Ｍｎ对Ｆｅ３Ａｌ合金化后的组织变化以及其对拉伸性能与断裂特征的影响进行了分析，结果表明，由于Ｍｎ对Ｆｅ３Ａｌ的合金化，而引入的具有面心立方有序结构的近Ｌ１２γ相，对Ｆｅ３Ａｌ的组织结构及拉伸性能产生了很大影响；随着Ｍｎ含量的增加，合金中ＤＯ３相的有序度降低；当Ｍｎ加入量适当时，可显著提高Ｆｅ３Ａｌ的室温强度和塑性，及合金的中高温塑性，但中高温强度衰减较大；总的说来，１０％Ｍｎ合金其塑性显著提高，室温强度大幅度提高，中高温强度与Ｆｅ３Ａｌ相当．     

PBT／PET共聚酯及其纤维的热性能

本文利用差示扫描量热分析（ＤＳＣ）研究了ＰＢＴ／ＰＥＴ共聚酯及其纤维热性能与形态结构的关系．实验结果表明ＰＢＴ／ＰＥＴ共聚酯高温稳定性好，其结晶结构为ＰＢＴ／ＰＥＴ共晶结构，随ＰＢＴ含量增加，其熔融热增加，熔点下降，ＰＢＴ／ＰＥＴ共聚纤维的熔融热随拉伸倍数增加而增加，这表明纤维结晶度随拉伸倍数而增加．适宜于ＰＢＴ／ＰＥＴ共聚纤维的拉伸温度为８０℃．     

亚高温作用下国产ECC早期力学性能研究

为研究不同亚高温作用下国产高延性水泥基复合材料（ECC）的早期力学特性,通过抗压试验、单轴拉伸试验、四点弯曲试验和断裂性能试验,分析了50℃、100℃、150℃、200℃4种不同亚高温作用下国产ECC早期抗压性能、拉伸性能、弯曲性能及断裂性能的变化规律。试验结果表明：亚高温有利于国产ECC早期抗压强度及断裂韧度的提升,其抗压强度和断裂韧度均随温度的升高逐渐增强;50℃的亚高温作用可提高国产ECC早期拉伸性能与弯曲性能;100℃温度作用下,国产ECC部分力学特性已经劣化,但仍具有优异的抗变形能力;在温度继续升高后,国产ECC早期抗变形能力明显减弱,但强度性能得到显著提升;国产ECC经不同亚高温作用后仍可保持良好的早期力学性能。     

预变形对X60管线钢拉伸性能的影响

通过拉伸试验，分析了预拉伸变形对X60管线钢拉伸性能的影响。结果表明：预拉伸变形增大了X60管线钢的屈服强度、抗拉强度，降低了材料的塑韧性；随着预变形量的增加，X60管线钢的断裂延性明显降低．断裂强度增加，呈现明显的加工硬化现象。     

TiAl＋Ca合金断裂及变形亚结构研究

运用ＳＥＭ和ＴＥＭ等分析手段研究了ＴｉＡｌ＋Ｃａ三元合金的室温断裂行为和变形亚结构，结果表明，少量Ｃａ的添加可以大幅度提高Ｔｉ－３４％Ａｌ合金的室和学性能，合金断裂时不再表现为单纯的穿晶解理断裂而在γ单相中出现的河流状的解理纹，断口上还出现较多的撕裂梭；ＴＥＭ分析表明，Ｃdisplay status     

Microstructure and Mechanical Behavior of Squeeze Casting Mg-8Gd-2Y-0.4Zr Alloy

Microstructure and mechanical behavior of the squeeze-casting and squeeze-casting plus T6 heat-treated Mg-8 Gd-2 Y-0.4 Zr magnesium alloys at room and elevated temperatures were investigated. The experimental results showed that the T6 treated alloy aged at slightly high temperature exhibited good comprehensive strength and ductility. However, the strength of the tested alloys was not sensitive to the change of tensile temperature, i e, the yield strength and ultimate tensile strength did not decrease significantly with increasing tensile temperature, while the ductility increased greatly. In addition, the squeeze-casting alloy exhibited predominant intergranular fracture accompanied by minor transgranular rupture, and the tensile fracture mode for the T6 treated alloy had typical transgranular cleavage fracture.     

Effect of rare earth elements on the microstructure and property for magnesium alloy AM60B

The effects of rare earth elements on the microstructure and properties of magnesium alloy AM60B alloy were studied.Different proportions of rare earth elements were added to AM60B and the tensile tests were carried out under different temperatures.The experimental results show that at room temperature the tensile strength of AM60B can be improved with the addition of rare earth elements.The ductility of which at room or elevated temperature(120℃） can also be improved ,and the ductility is to some extent in proportion with the amount of rare earth elements.The ductility at 120℃ is better than that at room temperture,The microstructure graphs demonstrate that appropriate amount of rare earth elements (0.1%-0.2%,mass fraction)can fine AM60B‘s grain and improve its ductility.     

淬火温度对Zr-4合金显微组织和拉仲性能的影响

为探讨不同淬火温度对核燃料包壳管Zr-4合金力学性能的影响．本文分析了Zr-4合金的显微组织,通过对再结晶退火态的Zr-4合金进行不同温度淬火及回火热处理,在不同热处理状态下对试样进行室温环向拉伸试验,分析对比了试样的拉伸力学性能,并对拉伸后的试样进行断口扫描,分析断裂机理．试验结果表明：包壳管Zr-4合金在980℃淬火后晶粒弦长为145．62μm,相比920℃、950℃的弦长增大,其抗拉强度为740MPa,屈服强度为649MPa．淬火后断口类型属解理脆性断裂．     

渗碳对Fe_3Al基合金力学性能的影响

通过研究 F e3A l基合金经不同时间渗碳后其室温力学性能和高温力学性能的变化 ,发现碳的渗入使合金的强度与延伸率都有所下降 ,同时 F e3A l合金的有序转变温度 Tc升高 .C以固溶形式进入F e3A l合金 ,当 C渗入量超过其固溶度时 ,将在晶界处析出碳化物从而降低合金的强度与塑性     

镍基单晶高温合金不同温度下的拉伸性能

为了研究一种镍基单晶高温合金从室温到1100℃范围的拉伸变形与断裂行为,利用扫描电子显微镜和透射电子显微镜对拉伸断口及变形后位错组态进行观察和分析.结果表明：合金的屈服和抗拉强度均在约800℃时达到峰值,而塑性与强度的变化规律基本相反.室温和中温拉伸条件下,断口表现为解理断裂;而高温时则为微孔聚集型断裂.室温拉伸条件下,合金的主要变形方式为单根位错剪切γ′相;高温下为位错绕过γ′相;中温下则表现为由剪切到绕过的过渡.     

Effects of rare earth elements on the microstructure and properties of magnesium alloy AZ91D

The effects of rare earth elements on the microstructure and properties of Magnesium alloy AZ91D alloy were studied.The different proportion of rare earth elements was added to the AZ91D and the tensile tests were carried out at different temperatures.The experimental results show that at room temperature or at 120℃ the AZ91D‘s decrease with the increasing amount of the rare earth elements.however,the ductility is improved.The influence of 0.14%Sb(mass fraction)on the AZ91D‘s strength is like that of rare earth elements(0.2%-0.4%)(mass fraction).Microstructure graphs demonstrate that appropriate amount of rare earth elements (0.1%-0.2%) can fine AZ91D‘s grain and improve its ductility.     

Dynamic mechanical behavior and microstructural evolution of the Al-6Mg alloy subjected to three treatment conditions

The mechanical properties of Al-6Mg alloy with three treatment states (H112, O and cold-extruded states) were investigated at room and high temperatures using an INSTRON machine and a Split Hopkinson Pressure Bar (SHPB). Stress-strain curves of the alloy with different processes were obtained at a quasi-static strain rate of 5×10-4 s-1and dynamic strain rates of 1 400-4 200 s-1, respectively. The results suggest that, at room temperature, the three processed Al-6Mg alloys are all low sensitive to strain rate. The O state Al-6Mg alloy (Al-6Mg-O) exhibits the most ductility, while the cold-extruded Al-6Mg alloy (Al-6Mg-C) displays the highest strength. At elevated temperatures, the yield stresses and the differences in yield stress of the three processed alloys all decrease with increasing temperature under the quasi-static strain rate of 5×10-4 s-1. Based on test results, modified Johnson-Cook (JC) constitutive models for the three processed Al-6Mg alloys were developed. The microstructures before and after deformation were examined by electron backscattered diffraction (EBSD) and further dynamic recrystallization (DRX) at the strain rate of 3 300 s-1 was discussed.     

Temperature distribution for controlled-dwell extrusion of γ-TiAl

Ti-47Al-2Cr-2Nb-0. 15B alloy (atom fraction) was extruded at temperatures(Tα) of 1 250 and 1 330 ℃,respectively. The method of adding a thermal insulating layer was used to overcome the problem associated with the flow stress mismatch Between the can and the billet during extrusion. Effects of two kinds of insulations, ZrO2 powders and silica fibers, on the quality of extrude bar along the radial direction were studied, and the process parameters were optimized by combining with finite element method (FEM). Tensile properties of the extruded alloy at room and elevated temperature were tested. The results show that the silica fibers has better thermal insulating property than ZrO2 powders. The temperature distribution in radial is more homogeneous using silica fibers. The alloy has a good balance of yield strength and room temperature ductility and the values are 680 MPa and 3.5 %, respectively.     

金属间化合物NiAl的合金化与凝固技术

详细介绍和评述了金属间化合物NiAl的合金化与凝固技术的研究现状，并重点介绍了合金化对NiAl合金的塑性、韧性和强度的影响，以及定向凝固，普通铸造和单晶制备技术对NiAl合金强韧化的影响。其中，定向凝固技术制备的NiAl基与难熔金属相组成的共晶合金具有良好的综合力学性能，既具有较高的高温强度，又具有较好的室温韧性。     

拉伸变形对AA6016铝合金汽车外板再结晶组织及性能的影响

为优化冲压成形工艺,研究了不同拉伸形变量对T4P态AA6016冷轧薄板再结晶、析出行为、烘烤硬化性及断裂方式的影响规律.采用与气垫炉生产线类似的新型热处理设备,对合金进行固溶处理,预时效后室温停放,获得T4P态合金.以单向拉伸模拟板材局部冲压成形过程,采用金相显微镜、扫描电镜和透射电镜,对合金再结晶组织、拉伸断口以及位错进行观察,并结合DSC测定和拉伸性能测定,对合金析出行为及力学性能表征.结果表明:随拉伸形变量增加,局部晶粒有被拉长的趋势;形变可抑制GP区溶解,并促进强化相析出;烘烤硬化性随形变增加而减弱;形变较小时,烘烤前后断裂方式均为塑性断裂,而形变较大时,烘烤前合金更加趋向于解理断裂,烘烤后解理断裂趋势减弱.