脉冲电流对Zn—22Al合金超塑性力学行为的影响

本文以普通处理的Ｚｎ－２２Ａｌ合金板坯为对象，研究了脉冲电流对其超塑性力学行为的影响，实验结果表明：在脉冲电流作用下，合金的延伸率和应变速度敏感性指数有了很大提高，流动应力降低，在高应变速率下，该合金仍具有很高的延伸率，最佳超塑变形温度向低温度方向偏移，合金的超塑变形可在更低温度下进行。     

微量Mg,Ag对Al—Li—Cu系合金性能和组织的影响

在ＡＡ２１９５标准成分基础上,通过加入微量元素Ｍｇ和Ａｇ,研究了各合金薄板材料在１８０℃不同时效时间下的室温拉伸性能和湿微组织特征,实验结果表明：单独加入Ｍｇ和单独加入Ａｇ对Ａｌ－Ｌｉ合金都有强化效果,但Ａｇ的单独作用显然比Ａｇ要大得多。Ｍｇ和Ａｇ共同加入则产生最大的强化效应,这说明Ｍｇ和Ａｇ之间有强烈相互作用。     

铸造用Zn—Al合金超塑性的研究

主要对工业牌号Ｚｎ－Ａｌ合金ＺＡ８，ＺＡ１２和ＺＡ２７进行了组织超塑性研究，发现经地组织细化的ＺＡ８，ＺＡ１２和ＺＡ２７铸造Ｚｎ－Ａｌ合金，在２７０～３３０℃温度区间和８．３×１０＾－４～１．７×１０＾－２ｓ＾－１初始应变速率（ε０）的试验条件下具有主好的超塑性力学性能，并且在较低的温度条件下也具有一定的超塑性特点。     

工业用超塑性Zn—22Al合金的内耗峰

用低频倒扭摆测量了超塑性 Zn-22Al 合金的内耗。实验观察到在频率0.75HZ 的内耗-温度曲线上出现了118℃、190℃两个稳定的弛豫峰:随着扭转频率增加,峰值移向高温区,两种弛豫的激活能分别为:H_1=12.3×10~4J/mol,H_2=17.3×10~4J/mol。还研究了不同预变形量对内耗的影响。随着变形量的增大,低温峰移向高温,峰高增加;高温峰的峰温不变,峰高也增加。但预变形量超过5%,低温峰又向低温移动,峰高降低;高温峰移向高温,峰高与5%预形变的峰高相等。整个实验的背底内耗随温度升高而增加,也随形变量增加而增加。     

微量Zr对Cu—Zn—Al合金冷变形能力的影响

研究了微量Ｚｒ对Ｃｕ－Ｚｎ－Ａｌ合金再结晶规律和机械性能的影响，结果表明，在该合金中添加０．２４％Ｚｒ再结晶温度升高，晶粒明显细化，但β相的含量也增多，使冷变形能提高不明显。     

脉冲电流对Zn－22Al合金超塑性力学行为的影响

本文以普通处理的Ｚｎ－２２Ａｌ合金板坯为对象，研究了脉冲电流对其超塑性力学行为的影响．实验结果表明：在脉冲电流作用下，合金的延伸率和应变速度敏感性指数有了很大提高，流动应力降低．在高应变速率（３．３×１０（－２）ｓ（－１））下，该合金仍具有很高的延伸率．最佳超塑变形温度向低温度方向偏移．合金的超塑变形可在更低温度下进行．     

Cu—Zn—Al合金应力诱发贝氏体相变

测定了母相状态的Ｃｕ－Ｚｎ－Ａｌ记忆合金，在恒应力作用下连续加热过程与中温等温过程的变形量。通过对温度－应变特性，时间－应变特性，组织形貌以及Ｘ光结构分析，揭示出了应力，温度及升温速度对应力诱发贝氏体相变的影响。     

Ageing behavior of an Al-Zn-Mg-Cu alloy pre-stretched thick plate

The ageing behavior of a pre-stretched thick plate of Al-Zn-Mg-Cu alloy was systemically studied including one-step ageing, two-step ageing, and retrogression and reageing treatment (RRA). One-step ageing of the alloy resulted in peak ultimate tensile strengths of 595 and 575 MPa after 22 and 6 h at 120 and 135°C, respectively. The strengthening phase in peak aged (T6 temper) alloy contained GP zones and the η′ phase predominantly. After two-step ageing, the electrical conductivity was increased markedly, but the pre-stretched thick plate sacrificed a great loss of strength. RRA treatment provided a method for maintaining the strength close to that obtained by T6 temper and for obtaining the high electrical conductivity close to that obtained by T7 temper; the ultimate tensile strength and electrical conductivity were 583 MPa and 21.0 MS/m, respectively. TEM analysis of T7 and RRA specimens revealed two types of precipitates that contributed to age strengthening i.e. the η′ and η phases.     

B93高强铝合金结晶相分析

采用光学显微镜、扫描电镜和能谱分析等手段,研究了不同处理状态下B93高强铝合金的显微组织和成分分布,并分析探讨了其显微组织的演变过程。结果表明,B93合金铸态组织中,主要元素Zn、Mg和Cu在晶界上存在不同程度的富集,形成骨骼状η(MgZn2)相和T(AlZnMgCu)相以及块状Al6(CuFe)相。热处理后,骨骼状相容易发生溶解,块状Al6(CuFe)相回溶较困难,Cu元素的偏析很难完全消除。合金棒材经过挤压后,T相(AlZnMgCu)和Al6(CuFe)相发生大幅度破碎,呈小尺寸碎粒子沿挤压方向分布,铸锭芯部出现S(Al2CuMg)相。     

Effect of heat treatment on microstructures and mechanical properties of a bulk nanostructured Al-Zn-Mg-Cu alloy

A bulk nanostructured Al-10.0Zn-2.8Mg-1.8Cu alloy was synthesized by cryomilling first and then by spark plasma sintering (SPS), and the effect of heat treatment on the microstructures and mechanical properties of this alloy were studied. Most MgZn_2 particles with a coarse size lie on the grain boundaries of the SPS-processed sample. After solid solution and artificial aging,fine spherical-like MgZn_2 particles precipitate uniformly in the grain interiors. No obvious grain growth is found after the heat treatment. A nanoindentation study indicates that no clear change is found in the Yong's modulus of the nanostructured alloy after the heat treatment.However, the hardness of the nanostructured alloy increases by about 33% after the heat treatment, which is attributed to the effect of precipitation-hardening.     

LF6铝合金超塑变形机理的研究

借助于高放大倍率的二次复型组织，观察了ＬＦ６铝合金超塑变形后的表面晶粒组织。对目前公认的晶界滑动（ＧＢＳ）、扩散蠕变（ＤＣ）、位错滑移（ＤＳ）三种变形机理在不同应变速率下变形时各自所占的比例进行了测定和计算。根据计算结果，讨论了三种变形机理在变形过程中的相互作用和协调关系。     

Al—6Mg合金超塑性变形与空洞的研究

本文研究了Al—6Mg合金超塑性拉伸变形中的力学特性和显微组织的变化。试验结果表明,合金在520℃以ε=8.33×10~(-4)S~(-1)的应变速率拉伸,得最高延伸率578%,流动应力为1.6MN/m~2,m=0.68,合金通过静态再结晶得到等轴晶粒(11μm)。并对空洞生核和扩展,空洞与变形机制、廷伸率以及断裂进行了探讨。     

M5锆合金塑性变形行为

了解锆合金塑性变形行为,为M5合金的工程应用提供数据.试验采用静态拉伸试验方法对国产及法国产M5锆合金核燃料包壳管在室温和400℃下的拉伸性能进行了研究.结果表明,国产及法国产M5合金的拉伸性能无显著差异.在均匀塑性变形阶段,室温拉伸时法国产M5的形变硬化指数稍高于国产M5,400℃拉伸时两种材料的均匀塑性变形阶段均分为两个阶段,前均匀塑性变形阶段(n1)和后均匀塑性变形阶段(n2),法国产M5的n1明显高于国产M5的n1,法国产M5的n2稍高于国产M5的n2.     

Influence of exfoliation corrosion on tensile properties of a high strength Al-Zn-Mg-Cu alloy

The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). After exfoliation corrosion immersion, blisters and corrosion pits can be seen on the sheet surface, which lead to loss of materials and notches. A number of intergranular cracks are observed to initiate at the bottom of the corrosion-induced notches and propagate rapidly into the bulk materials during tensile. Consequently, exfoliation corrosion results in significant loss of strength and brittle fracture. EBSD results show that the crack propagation path is primarily along the grain boundaries with misorientation of ~45°, and coincidence site lattice (CSL) boundaries are slightly more resistant to crack.     

缎铝LD7超塑性研究

对缎铝ＬＤ７ 以变形温度、变形速率和对材料的预处理方式为三因素,按正交设计进行高温拉伸试验,寻找最佳的超塑性条件． 经过淬火＋ 过时效＋ 温变形处埋,在５３０ ℃, ε＝ ２－７８ ×ｌ０ － ４ｓ－ １ 时,呈现出显著的超塑性,延伸率达２６０ ％ ; 而挤压状态和经过温变形处理后,在适当的变形条件下,材料都具有较好的塑性;正交试验分析结果表明：变形温度是影响ＬＤ７ 铝合金超塑性最显著的因素;显微观察表明：ＬＤ７ 铝合金由于第二相粒子的作用,具有稳定的微细组织结构,因而其超塑性效应明显,在超塑性变形时发生了动态再结晶     

FEM Analysis of Axisymmetrical Superplastic Piercing Process

In this paper, a superplastic constitutive equation is deduced under the condition of Mises's criterion, and on this basis an FEM fundamental equation for analyzing superplastic materials is derived. The FEM program of axisymmetrical superplaseic deformation SPF1 is set up. The problems of deformation in the axisymmetrical piercing process are analyzed with this program. Finally the deformation regularity of the superplastic hobbing of die cavitcs is analyzed, the result of which will be beneficial to the establishment of relevant process criteria.