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测量了Mn-Cu-Al三元合金(含56-60wt-％Mn,0-3.59wt-％Al)在-150—150℃的声频内耗,发现当试样在调幅线的温度范围内进行时效时,内耗随着时效时间的增加而增加,并在特定的时间内达到极大值.时效温度越高,达到极大值的时间越短.在时效一定的时间后出现马氏体相变峰和孪晶界面弛豫峰.相变峰随着时效时间的增加而向高温移动;弛豫峰则出现在15℃左右(频率约1kHz),测得其激活能是0.56eV. 在调幅线内时效使合金的硬度、强度及脆性墙加,Al元素有增加合金的强度而降低其内耗的作用.实验结果表明,在450℃时效2—3h,可得到合金的内耗和强度的最佳综合指标. 根据内耗、模量、金相检验和X射线分析的结果,认为调幅分解后产生的富Mn区是合金发生相变和高内耗的来源,也是合金的强度增加和韧性降低的原因.
The acoustic internal friction of Mn-Cu-Al ternary alloy (containing 56-60 wt-% Mn, 0-3.59 wt-% Al) at -150-150 ° C was measured and it was found that when the specimen was aged at the temperature range of the amplitude modulation line , The internal friction increases with the aging time and reaches the maximum value within a certain time.The higher the aging temperature, the shorter the time to reach the maximum value.The martensitic transformation peak appears after a certain period of aging And twins interface relaxation peak phase transition peak as the aging time to move to high temperature; relaxation peak appears at about 15 ℃ (frequency of about 1kHz), the measured activation energy is 0.56eV in the modulation line The aging makes the hardness, strength and brittleness of the alloy increase, and the Al content increases the strength of the alloy to reduce its internal friction.The experimental results show that the optimum composite index of internal friction and strength of the alloy can be obtained by aging at 450 ℃ for 2-3h According to the results of internal friction, modulus, metallographic examination and X - ray analysis, it is considered that the Mn - rich zone generated after AM decomposition is the source of phase transformation and high internal friction of the alloy, which is also the reason for the increase of the strength and the decrease of the toughness of the alloy.