Effects of Y2O3 additions on mechanically alloyed and sintered W—4wt.% SiC composites

Normal ve Kriyojenik Şartlarda Öğütmenin Aktive Edilmiş Sinterleme Süreçleri ile Geliştirilen Tungsten Esaslı Kompozitlerin Mikroyapı ve Özellikleri Üzerindeki Etkisi

“…On the other hand, W or Ni based intermetallic compound (such as W5Si3, NiTi etc.) or WC contamination was not identified after sintering at 1400 ºC, as shown in Figure 3: These phases have been already reported for the sintered W matrix composites reinforced with carbide/boride and oxide particles [12,19,20]. The present result can be attributed to the proper amount of the reinforcement (2 wt.…”

“…Furthermore, any diffraction peak belonging to a secondary phase was not detected after milling at different conditions, indicating that no reaction took place between W, Ni, TiB2 and Y2O3 particles. WC contamination was previously observed for the W composites mechanically alloyed for 24 h using a high energy ball mill (1200 rpm) in a WC vial with WC balls with a BPR of 10:1 [20]. However, the XRD patterns in Figure 1 do not show the emergence of WC phase in the broad W peaks after milling at different conditions, most likely due to its very small content in the W matrix.…”

“…However, the XRD patterns in Figure 1 do not show the emergence of WC phase in the broad W peaks after milling at different conditions, most likely due to its very small content in the W matrix. Therefore, milling for 12 h is a sufficient milling time without any WC contamination in visible amount, considering the milling times in literature [20,24]. To reveal the effect of different milling types under ambient and/or cryogenic condition on the composite powders, the average crystallite sizes and lattice strains of the W phase in the milled powders (S1, S2 and S3) were determined ( Table 1).…”

“…Among the boride reinforcement particles, titanium diboride (TiB2) is an important ultra-high temperature ceramic with excellent properties such as high melting point, high temperature strength and good chemical resistance [17]. There are several researches reporting the fabrication and characterization of tungsten matrix composites reinforced with TiB2 and/or Y2O3 particles [18][19][20]. Furthermore, Ni powders added into the W by mechanical alloying process enables a rapid solidstate incorporation of the sintering aid into the matrix with an enhanced activation as well as particle size reduction [21].…”

Influence of Milling Media on the Mechanical Alloyed W-0.5 wt.% Ti Powder Alloy

“…Tungsten (W) alloys are attractive candidate materials for various high temperature structural applications due to their excellent properties such as high melting point, high modulus, high resistance of thermal shock, and low coefficient of thermal expansions (CTE) [1,2]. However, alloying of monolithic W is mandatory for applications which require high strengths at elevated temperatures since mechanical properties of monolithic W decrease significantly with increasing temperatures [3][4][5][6][7][8][9][10][11]. Small amounts of nickel (Ni) added as a transition element during mechanical milling (MM) and/or mechanical alloying (MA) activate sintering and enable the fabrication of fully dense W-based alloys and composites at lower temperatures than the usual sintering temperatures of W [7][8][9][10][11][12][13].…”