Abstract: The hardness variation of two kinds of alloys with 36% tungsten content and 7/3, 9/1 nickel-to-iron mass ratios during strain aging at 800℃ was studied. The microstructures of the aged alloys were analyzed by XRD and TEM. The results show that the strain aging hardness of W-Ni-Fe ternary alloy with 7/3 nickel-to-iron mass ratio decreases monotonically with the increase of aging time. Under the same conditions, however, the hardness of 9/1 nickel-to-iron mass ratio alloy decreases in the initial aging stage, and then increases as aging process goes on. XRD and TEM analysis show that there isn’t any precipitation depositing from the alloy with 7/3 nickel-to-iron mass ratio during aging. The monotonic decrease in hardness of this alloy during aging process results from the recovery, recrystallization and solid solubility declining. In the alloy of 9/1 nickel-to-iron mass ratio, the fine β phase precipitates dispersively during aging. Therefore, there are two different kinds of mechanisms influencing the hardness of the alloy with 9/1 nickel-to-iron mass ratio, one is recovery, recrystallization and solid solubility declining course, which softens the alloy, and the other one is the dispersion strengthening effect induced by the deposition of β phase, which hardens the alloy. These two mechanisms result in the hardness variation of the alloy with 9/1 nickel-to-iron mass ratio as mentioned above.
研究了钨含量为36%,Ni与Fe质量比为7/3和9/1的两种W Ni Fe三元合金的预应变时效硬度变化规律,用X射线衍射鉴定了时效后两种合金的物相组成,并用透射电镜观察其微观结构。结果表明:Ni与Fe质量比为7/3的W Ni Fe三元合金在800℃下进行预应变时效时,硬度随时间增加而单调降低;相同条件下Ni与Fe质量比为9/1的W Ni Fe三元合金时效初期硬度下降,但随时间延长硬度又逐步提高。X射线衍射物相鉴定和透射电子显微分析发现:Ni与Fe质量比为7/3的合金在预应变时效过程中没有明显沉淀析出物,其时效硬度下降是固溶度降低、残余应力消除以及回复与再结晶的结果;而Ni与Fe质量比为9/1的合金经预应变时效后析出了细小弥散的β相,其硬度变化存在两种机制,一种是固溶度降低、残余应力消除和回复与再结晶引起软化,另一种是细小β相沉淀析出导致弥散强化。
Strain aging of W-Ni-Fe ternary alloys with low tungsten content
Abstract：
The hardness variation of two kinds of alloys with 36% tungsten content and 7/3, 9/1 nickeltoiron mass ratios during strain aging at 800 ℃ was studied. The microstructures of the aged alloys were analyzed by XRD and TEM. The results show that the strain aging hardness of WNiFe ternary alloy with 7/3 nickeltoiron mass ratio decreases monotonically with the increase of aging time. Under the same conditions, however, the hardness of 9/1 nickeltoiron mass ratio alloy decreases in the initial aging stage, and then increases as aging process goes on. XRD and TEM analysis show that there isnt any precipitation depositing from the alloy with 7/3 nickeltoiron mass ratio during aging. The monotonic decrease in hardness of this alloy during aging process results from the recovery, recrystallization and solid solubility declining. In the alloy of 9/1 nickeltoiron mass ratio, the fine β phase precipitates dispersively during aging. Therefore, there are two different kinds of mechanisms influencing the hardness of the alloy with 9/1 nickeltoiron mass ratio, one is recovery, recrystallization and solid solubility declining course, which softens the alloy, and the other one is the dispersion strengthening effect induced by the deposition of β phase, which hardens the alloy. These two mechanisms result in the hardness variation of the alloy with 9/1 nickeltoiron mass ratio as mentioned above.
