The mechanical behavior of a cryomilled Al-10Ti-2Cu alloy
The mechanical behavior of a cryomilled Al-10Ti-2Cu alloy
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DOI：
10.1016/s1359-6454(01)00278-6
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发表时间：
2001-11
期刊：
影响因子：
9.4
通讯作者：
R. Hayes;R. Rodriguez;E. Lavernia
中科院分区：
文献类型：
--
作者：
R. Hayes;R. Rodriguez;E. Lavernia
通过在室温至525℃温度范围内进行单轴拉伸试验，研究了深冷Al-10Ti-2Cu(wt.%)合金的力学行为，在所有温度下都观察到了弹性-接近理想塑性的应力-应变行为。还观察到了室温屈服应力的拉压不对称性。这些特性与最近文献中报道的单相NC材料的特性是一致的。随着温度的升高，流动应力(室温下为700 Mpa)急剧下降。热暴露后对材料的测试表明，仅靠微结构粗化不能解释强度随温度升高而降低的原因。从粗化的角度来看，这种材料似乎具有很强的热稳定性。延性受多种因素的影响。较低的内部孔隙率以及细小的氧化物和碳化物弥散体的存在导致延展性较低。Al-10Ti-2Cu的无加工硬化也导致了应变降低到失效。断口观察到的特征表明，断裂是通过颗粒-基质界面空洞的形核和长大而发生的。沿先前粉末颗粒边界的断裂证据也存在。显微组织主要由含有30-70 nm范围内的颗粒的区域组成。还存在由名义上的纯Al组成的大颗粒区域，尺寸从300到500 nm不等。在AS挤压材料中，无论是细晶区还是粗晶区，都没有发现位错活动的证据。在室温和93℃下变形的样品显示出大晶区内位错活动的证据。位错组态表明为Orowan旁路机制。拉伸变形后，30-70 nm尺寸的晶内没有位错。
The mechanical behavior of a cryomilled Al–10Ti–2Cu (wt.%) alloy has been studied by performing uniaxial tension tests at temperatures ranging from room temperature to 525°C. Elastic–nearly perfectly plastic stress–strain behavior is observed at all temperatures. Tension–compression asymmetry of the room temperature yield stress is also observed. These characteristics are in agreement with those recently reported in the literature for single-phase NC materials. The flow stress (700 MPa at room temperature) decreases dramatically with increasing temperature. Testing of material following thermal exposures suggests that microstructural coarsening alone cannot account for the decrease in strength with increasing temperature. From a coarsening standpoint, this material appears to be very thermally stable. The ductility is influenced by several factors. Low levels of internal porosity along with the presence of fine oxide and carbide dispersoids contribute to lower ductility. The absence of work hardening exhibited by the Al–10Ti–2Cu also leads to reduced strain to failure. The features observed on fracture surfaces suggest that fracture occurs by the nucleation and growth of voids at particle–matrix interfaces. Evidence of fracture along prior powder particle boundaries is present as well. The microstructure consists primarily of regions containing grains measuring in the range 30–70 nm. Large grained regions consisting of nominally pure Al ranging in size from 300 to 500 nm are also present. No evidence of dislocation activity within either the fine or large grained regions can be found in the as extruded material. Specimens deformed at room temperature and 93°C reveal evidence of dislocation activity within the large grain regions. Dislocation configurations suggest an Orowan bypass mechanism. No dislocations are found within the 30–70 nm size grains following tensile deformation.