纯钨经高压扭转后韧性及热稳定性观察

Observations on the ductility and thermostability of tungsten processed from micropowder by improved high-pressure torsion

摘要:

采用高压扭转法，在440℃对纯钨进行大塑性变形(HPT)。硬度测试表明试样表面纯钨经高压扭转后硬度高达1150HV。差热分析(DSC)结果表明等效应变较小的试样再结晶温度较高(高于1450℃)，等效应变较大的试样再结晶温度较低(约800℃)。XRD分析结果表明试样晶格应变达0.35%，晶格常数达0.3177 nm，位错密度达2.4 × 1015 m-2。高压扭转可以使纯钨在低温下实现固结并具有高强度，一定的韧性和热稳定性。

Abstract:

Tungsten was subjected to severe plastic deformation at 440°C using high pressure torsion (HPT) with an improved die-set. Microhardness measurements suggest an appreciable ductility level in tungsten after HPT with Vickers microhardness as high as ~1150 HV. Differential scanning calorimetry (DSC) analyses showed that samples that developed less strain had a higher recrystallisation temperature (greater than 1450°C) than samples that developed more strain (~800°C). X-ray diffraction analyses indicate increases in lattice strain of up to 0.35%, lattice parameter up to 0.3177 nm and dislocation density up to 2.4 × 1015 m-2. The current study introduces the improved HPT process as an effective route for the production of ultrahigh strength W with significant ductility and specified thermostability.