Ni/Al微叠层复合板的成形性能

Formability of Ni/Al micro-laminated composite sheet

摘要:

采用真空热压法制备了Ni/Al微叠层复合板。通过不同温度、不同变形量下的单向拉伸实验研究了Ni/Al微叠层复合板的力学性能与裂纹萌生扩展规律。结果表明，Ni/Al微叠层复合板在室温至400℃塑性较差，变形量仅为5%时，NiAl3和Ni2Al3金属间化合物层便已产生较多垂直于拉伸方向的裂纹。Ni/Al微叠层复合板600℃表现出良好的塑性变形能力，断裂延伸率高达56%，且变形量达到20%时NiAl3层才开始出现微裂纹，变形量达到50%时裂纹仍未扩展至Ni2Al3层及Al层。采用气压自由胀形实验研究了Ni/Al微叠层复合板600℃条件下的成形性能，并对胀形件微观组织分布进行了表征。结果表明，Ni/Al微叠层复合板600℃/5.5MPa/8min条件下，极限胀形率(极限胀形高度/凹模直径)达36.7%。胀形球壳由底部至顶部壁厚逐渐减小，顶部Ni、Al层颈缩严重，NiAl3层产生裂纹，但并未扩展至Ni2Al3层及Al层。

Abstract:

The Ni/Al micro-laminated composite sheet was prepared by the vacuum hot pressing method. The mechanical properties and crack initiation and propagation laws of Ni/Al micro-laminated composite sheet were studied through uniaxial tensile experiments under different temperatures and different deformations degree. The results show that the Ni/Al micro-laminated composite sheet has poor plasticity from room temperature to 400°C, and when the deformation is only 5%, the NiAl3 and Ni2Al3 intermetallic compound layer has produced more cracks perpendicular to the tensile direction. The Ni/Al micro-laminated composite sheet exhibits good plastic deformation ability at 600℃, with the elongation at break as high as 56%, and when the deformation reaches 20%, the NiAl3 layer begins to appear microcracks, and the crack does not propagate to Ni2Al3 layer and Al layer when the deformation reaches 50%. The pressure free bulging experiment was used to study the forming performance of the Ni/Al micro-laminated composite sheet at 600℃, and the microstructure distribution of the bulging part was characterized. The results show that the limit bulging rate (limit bulging height/die diameter) of Ni/Al micro-laminated composite sheet at 600℃/5.5MPa/8min can reach 36.7%. The wall thickness of the gas bulged spherical shell gradually decreases from the bottom to the top, the top Ni and Al layers were severely necked, and cracks occurred in the NiAl3 layer, but they did not extend to the Ni2Al3 layer and the Al layer.