<正> 为揭示快淬热压磁体热应变织构产生的根源,我们对合金机械性能随温度的变化进行了系统研究。前文报道了Nd-Fe-B磁体的热膨胀和硬度随温度的变化,本文则着重报道在室温到800℃温区内,Nd-Fe-B磁体的杨氏模量随温度的变化,以展示晶体刚度各向异性和塑性流变特性对热应变织构形成的可能贡献。 一般而言,合金的杨氏模量是结构不敏感的参量,即它与合金内部显微组织以及合金成分的微调无关。它主要反映合金内部原子之间的键合,故具
Young's modulus of Nd-Fe-B magnet within temperature range from 25 to 800℃was measured by means of ultrasonic resonance. E_∥ measured along c-axis is always smaller thanE_⊥, measured perpendicular to c-axis. The relative difference of Young's modulus (E_⊥-E_∥)/E_⊥=2.2% at room temperature remains almost the same till 500℃, whereas increases very sharplywhen T>500℃. Taking the value of aboat 12% at 600℃, i.e. 5 times more than the value atroom temperature. There is a step following a steep fall of both E_∥ and B_⊥ within the tempera-ture range of 550--600℃, which may be attributed to the melting of Nd-rich phase in the mag-net. Since Young's modulus reflects mainly the strength of bonding between atoms, i. e. thestiffness of the materials, the obtained results imply that the anisotropy of stiffness for Nd-Fe-Bmagnets becomes much higher at temperature above 600℃. Both the high anisotropy of stiff-ness and the remarkable softening at T>600℃ provide evidences for the mechanism of inducedtexture due to hot pressing.
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