A ceramic matrix composite includes continuous silicon carbide fibers in a ceramic matrix comprising silicon carbide and a MAX phase compound having a chemical composition M.sub.n+1AX.sub.n, where M is a transition metal selected from the group consisting of: Ti, V, Cr, Sc, Zr, Nb, Mo, Hf, and Ta; A is a group-A element selected from the group consisting of: Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl and Pb; and X is carbon or nitrogen, with n being an integer from 1 to 3.

A preparation method of submicron powder of high-entropy nitride via nitride thermal reduction with mechano-chemical assistance, comprising material preparationgrindingactivationpreformingreaction. In the present invention, high-entropy metal nitride and silicon nitride is used as raw materials, soft mechanochemical activation technologies are used to reduce reaction activation energy of the system, thereafter, by thermal reduction of the nitride, high-purity high-entropy nitride powder is prepared with solid phase methods, and the shortage of high-purity high-entropy nitride powder is addressed. There is no impure phase in the (Hf.sub.0.2Zr.sub.0.2Ti.sub.0.2Nb.sub.0.2Ta.sub.0.2)N high entropy powder prepared according to the present invention, and a single phase solid solution of good crystallinity is formed, and distribution of elements and ingredients in the powder is even, no foreign element is present, and oxygen content is controlled to be less than 0.3%.