【摘要】 采用低温球磨结合热压烧结技术制备了块体纳米铝晶体材料,在多功能内耗仪上采用受迫振动连续变温(25～450℃)的方式测量了纳米铝材料在低频率(0.2～3.0Hz)条件下的内耗和相对动力学模量。结果表明,纳米铝晶体材料受迫振动时,在升温和降温的内耗-温度谱上均出现一个内耗峰;伴随着内耗峰的出现,相对动力学模量明显下降;随着离散振动频率的增加,内耗峰峰位向高温方向移动,说明该内耗峰具有弛豫性;根据Arrhenius关系,得到该内耗峰的激活能为(2.21±0.04)×10-19 J、指数前因子τ0为10-14 s,表明该内耗峰是晶界内耗峰,其机制为铝原子在铝/铝晶界的自扩散。更多还原

【Abstract】 The bulk nanocrystalline aluminum were fabricated by cryomilling and hot-press sintering.The internal friction(IF) and relative dynamic modulus measurements in the nanocrystalline aluminum(Al) were made using a multifunction internal friction apparatus(MFIFA) at low frequencies(0.2-3.0 Hz) over the wide temperature ranges from 25 ℃ to 450 ℃,while continuously changing-temperature forced vibration measurement.In the temperature spectra of IF during heating process and cooling process,a distinct IF peak is found.Corresponding to the IF peak,the relative dynamic modulus decreases rapidly.The peak temperature of the IF peak shifts towards higher temperature with increasing frequency,i.e.,the IF peak seem due to the thermal activated relaxation process.The IF peak is a grain boundary IF peak,which is associated with the diffusive grain boundary of Al/Al.According to the Arrhenius relation,its activation energy has been calculated to be(2.21±0.04)×10-19 J and the pre-exponential factor τ0 is 10-14 s in IF measurements.更多还原