Sintered compact

1. A compact with a cubic boron nitride (cBN) portion and a non cBN portion, the compact comprising:

(a) between about 71 and about 93 volume-% cBN;

(b) between about 1 and less than_about 20 volume-% of aluminum oxide;

(c) between about 3 and about 26 volume-% of one or more refractory metal compounds selected from the group consisting of:

i. a compound having the general formula MZ (1-x) ;

ii. a compound having the general formula MC (1-x) Nx; and

iii. a combination or solid solutions of two or more compounds each having the general formula MZ or MZ 2 ; wherein:

Z is selected from the group consisting of C, B, N and combination thereof, M is a metal from any of groups IV-VI of the periodic table, and x is a number between 0.01 and 0.99; and

(d) between greater than 6 and about 20 volume-% of a source of one or more non-oxide aluminum compounds;

wherein the total aluminum content in the non cBN portion of the sintered compact exceeds about 30 weight-%

wherein the cBN has a grain size distribution that is at least bimodal having a coarse portion comprising about 40% to about 80% of the cBN and a fine portion comprising about 20 to about 60% of the cBN;

wherein the coarse portion has an average grain size of about 5 to about 30 μm and the fine portion has an average grain size of about 0 to about 10 μm; and

wherein the ratio of the average grain size of the coarse portion to the average grain size of the fine portion is about 3:1 or greater.

2. The compact of claim 1 , wherein the one or more refractory metal compounds comprise at least one of TiC (1-x) N x , or a mixture of at least two materials selected from the group of TiC, TiN, TiB 2 , TiN (1-x) and TiC (1-x) N x , wherein x is a number between 0.01 and 0.99.

3. The compact of claim 1 , wherein the compact is in an unsupported form.

4. The compact of claim 1 , wherein at least a portion of aluminum that forms the one or more non-oxide aluminum compounds originates from a foil or other solid form of metallic aluminum placed in contact with a powder mixture during sintering.

5. A compact with a cubic boron nitride (cBN) portion and a non cBN portion, the compact comprising:

(a) between about 50 and about 93 weight-% of cBN with at least a bimodal grain size distribution;

(b) between about 1 and about 30 weight-% of aluminum oxide;

(c) between about 3 and about 46 weight-% of one or more compounds selected from the group consisting of carbides, nitrides, borides, and carbonitrides, all of groups IV-VI of the periodic table, and mixtures and solid solutions thereof; and

(d) between greater than 6 and about 30 weight-% of one or more non-oxide aluminum compounds;

wherein the total aluminum content in the non cBN portion of the sintered compact exceeds about 10 weight-% of the compact;

wherein the cBN has a grain size distribution that is at least bimodal having a coarse portion of about 40% to about 80% of the cBN; and a fine portion of about 20 to about 60% of the cBN;

wherein the coarse portion has an average grain size of about 5 to about 30 μm;

wherein the fine portion has an average grain size of about 0 to about 10 μm; and

wherein the ratio of the average grain size of the coarse portion to the average grain size of the fine portion is about 3:1 or greater.

6. The compact of claim 5 , wherein the one or more compounds selected from the group consisting of carbides, nitrides, borides, and carbonitrides, are carbonitrides of the formula TiC (1-x) N x , or a mixture of at least two materials selected from the group of TiC, TiN, TiB 2 , TiN (1-x) and TiC (1-x) N x , wherein x is any value between 0.01 and 0.99.

7. The compact of claim 5 , wherein the compact is in an unsupported form.

8. The compact of claim 5 , wherein at least a portion of aluminum that forms non-oxide aluminum compounds originates from a foil or other solid form of metallic aluminum placed in contact with the powder mixture during sintering.