Microstructure and performance of rare earth element-strengthened plasma-facing tungsten material.

Laima Luo,Xiang Zan,Jinshan Lin,Jing Shi,Qiu Xu,Yucheng Wu,Xiaoyong Zhu

doi:10.1038/srep32701

Abstract

Pure W and W-(2%, 5%, 10%) Lu alloys were manufactured via mechanical alloying for 20 h and a spark plasma sintering process at 1,873 K for 2 min. The effects of Lu doping on the microstructure and performance of W were investigated using various techniques. For irradiation performance analysis, thermal desorption spectroscopy (TDS) measurements were performed from room temperature to 1,000 K via infrared irradiation with a heating rate of 1 K/s after implantations of He+ and D+ ions. TDS measurements were conducted to investigate D retention behavior. Microhardness was dramatically enhanced, and the density initially increased and then decreased with Lu content. The D retention performance followed the same trend as the density. Second-phase particles identified as Lu2O3 particles were completely distributed over the W grain boundaries and generated an effective grain refinement. Transgranular and intergranular fracture modes were observed on the fracture surface of the sintered W-Lu samples, indicating some improvement of strength and toughness. The amount and distribution of Lu substantially affected the properties of W. Among the investigated alloy compositions, W-5%Lu exhibited the best overall performance.

Highlights

Pure W and W-(2%, 5%, 10%) Lu alloys were manufactured via mechanical alloying for 20 h and a spark plasma sintering process at 1,873 K for 2 min
The International Thermonuclear Experimental Reactor (ITER) program will demonstrate the scientific validity and viability of secure fusion energy by burning deuterium (D)-tritium (T) plasma integrated with key reactor technologies[1]
Powder agglomeration was observed for all the powders, and the degree of agglomeration increased with increasing LuH2 content

Summary

Introduction

Pure W and W-(2%, 5%, 10%) Lu alloys were manufactured via mechanical alloying for 20 h and a spark plasma sintering process at 1,873 K for 2 min. The W material will be exposed to substantially high heat fluxes and to intense neutron and hydrogen isotopes and helium (He) plasma radiation during long-term operation of a fusion reactor. These circumstances will give rise to changes in the surface morphology, leading to retention of hydrogen isotopes and helium (He), blistering in W, and dramatic impairment of the thermal and mechanical performances of W. The reinforcement mechanism of alloyed W mainly includes solution and interface strengthening Alloying elements such as Re, Hf, Zr, and Nb help modify impurity distributions and effectively www.nature.com/scientificreports/. Low D or T retention is a key parameter for estimating the applicability of a first wall material and is vital for efficiency, safety, and economic concerns[16,17]

Methods

Results

Conclusion