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Microstructure and cutting performance of titanium carbide cermets containing nitrogen
PM
Coatings DETONATION COATING P R O C E S S E S
V. Kadyrov et al (Academy of Sciences, Kiev, Ukraine), Trans. PM Assoc. of India, Vol 20, 1993, 1-5. The d e t o n a t i o n process is described in which m e t a l powder is d e p o s i t e d on a s u b s t r a t e with explosive force. Equipment, physico-chemical reactions, m e t a l l o g r a p h y of t h e c o a t i n g s a n d a p p l i c a t i o n s a r e discussed.
Electrical and magnetic materials E F F E C T S OF HEAT TREATMENT ON MICROSTRUCTURE AND COERCIVITY OF IRON-NEODYMIUM-BORON
LITERATURE
REVIEW
It is r e p o r t e d t h a t sintering of WiB2with Fe results in t h e f o r m a t i o n of Fe2B t h u s a b s o r b i n g some of t h e ductile b i n d e r phase, Ti203 also forming t h i s being a t t r i b u t e d to impurities. The use of a m e t a l b i n d e r w i t h a g r e a t e r a f f i n i t y f o r B t h a n Fe w a s i n v e s t i g a t e d a n d single p h a s e Fe-Cr-Ni a n d two p h a s e Fe2B-Fe-Ni-Cr b i n d e r s were studied with b i n d e r c o n t e n t s in t h e r a n g e 5 to 20vo1%. It is r e p o r t e d t h a t b e t t e r hardness/fracture toughness combinations were o b t a i n e d t h a n with WC-Co or Ti (C,N) cermets. The use of fine grained TiBzB, w i t h low O a n d C contents, shows p o t e n t i a l for f u r t h e r d e v e l o p m e n t as t h e s e will give i m p r o v e d sintering, m i c r o s t r u c t u r e s a n d properties. HEALING OF CRACKS IN T U N G S T E N CARBIDE-COBALT IN THE T E M P E R A T U R E RANGE 600°C TO 800°C
J.P. Yang et al (Korea Advanced Inst. of Science a n d Technology, Korea), Materials Science and Engineering B, Vol B18, No 1, 1993, 78-82. A r e p o r t of investigations into t h e effects of cyclic h e a t i n g a n d cooling o n t h e m i c r o s t r u c t u r e a n d magnetic p r o p e r t i e s of sintered Fe-Nd-B m a g n e t s is presented. The v a r i a t i o n in coercivity is s h o w n to be reversible d e p e n d i n g on cooling rate. Assintered or cooled at 4.5°C/min t h e r e was low coercivity b u t on r a p i d cooling at 200°C/min the coercivity was high. This is a t t r i b u t e d to t h e presence of a h e x a g o n a l Nd rich p h a s e in t h e fast cooled alloys.
W. B a r l o w - J o n e s e t al ( U n i v e r s i t y of Witwatersrand, J o h a n n e s b u r g h , S o u t h Africa), Int. J. Refractory Metals & Hard Materials, Vol 12, No 2, 1993-1994, 89-93. It is r e p o r t e d t h a t cracks in WC-Co partially heal when annealed. An investigation of WC-6%Co a n d WC-10%Co, h e a t t r e a t e d a t 600, 700 or 800°C, is described. A m o d e l is p r o p o s e d w h i c h agrees well with t h e e x p e r i m e n t a l results. Healing is a t t r i b u t e d to re-sintering in t h e b i n d e r p h a s e only w h e n t h e crack interface s e p a r a t i o n is small e n o u g h for asperities in t h e surface to bridge t h e crack, mainly n e a r to t h e crack tips.
Hard materials and tool steels
TURNING T E S T S WITH TITANIUM DIBORIDE C E R M E T S
PROPERTIES OF HIP AND S I N T E R E D HIGH S P E E D S T E E L
K Veda et al (Mitsubushi Materials Corporation, Omiya, J a p a n ) , J. Japan Soc. Powder and Powder MeLallurgy, Vol 40, No 6, 1993, 589-592. (In Japanese). A c o m p a r i s o n is m a d e between HSS p r o c e s s e d by HIP or by c o n v e n t i o n a l sintering. The HIP steel is r e p o r t e d to have s u p e r i o r p r o p e r t i e s a f t e r v a c u u m sintering. It is n o t e d t h a t HIP p a r t s can be m a d e to closer d i m e n s i o n a l t o l e r a n c e s (60 I~m) c o m p a r e d with 150 I~m for t h e conventionally sintered steel. The HIP steel h a s the higher s t r e n g t h at 365 Kgf/mm 2 c o m p a r e d with 270 Kgf/mm '~. NEW HARD METALS BASED ON TITANIUM DIBORIDE
L.S. Sigl et al (Electroschmelzwerk Kempten, Kempton, Germany), Int. J. Refractory Metals & Hard Materials, Vol 12, No 2, 1993-1994, 71-88.
L.S. Sigl et al (Electroschmelzwerk Kempten, Kempten, Germany), Int. J. Refractory Metals & Hard Materials, Vol 12, No 2, 1993-1994, 95-99. The cutting performance of TiB2 cermets, against a C steel, a cast iron a n d a hypoeutectic A1-Si alloy were c o m p a r e d with Ti(C,N)-Ni a n d A1203-ZrO 2. The WiB2 materials are r e p o r t e d to show s u p e r i o r performance in spite of a coarse m i c r o s t r u c t u r e a n d p o o r high t e m p e r a t u r e s t r e n g t h in t h e b i n d e r p h a s e w h e n used to cut cast iron a n d A1-Si. It is considered t h a t f u r t h e r i m p r o v e m e n t s are r e q u i r e d a n d work to a t t a i n this is said to be in progress. MICROSTRUCTURE A N D CUTTING PERFORMANCE OF TITANIUM CARBIDE C E R M E T S CONTAINING NITROGEN
M. Ueki (Toshiba Tungaloy Co, Kawasaki, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 7, 1993, 743-750. (In Japanese).
A n i n v e s t i g a t i o n o f t h e e f f e c t s of a d d i t i o n s of TaC, NbC or WC o n t h e m i c r o s t r u c t u r e s a n d cutting p e r f o r m a n c e of TiC-20vol%TiN-7%Mo2C-8%Ni and c h a n g e s c a u s e d by h e a t t r e a t m e n t is described.
Intermetallic materials HIP P R O C E S S I N G OF TITANIUM ALUMINIDE FROM B L E N D E D ELEMENTAL POWDERS
P. Lee-Sullivan, J. Materials Processing Technology, Vol 38, No I-2, 1993, 483-489. The p r o d u c t i o n of ~ from b l e n d e d equiatomic m i x t u r e s of e l e m e n t a l powders by HIP or by CIP followed by contalnerless HIP, is described. The HIP alloy is shown to consist of e q u i a x e d TiA1. In t h e CIP/CHIP m a t e r i a l t h e r e was diffusion of A1 in Ti a n d t h e incomplete dissolution gave a m i x t u r e of 3fILM, a2TiaA1 with m u c h porosity.
PM components FIELD USE OF WEAR R E S I S T A N T PM MATERIALS
J. Potschke (Krupp Pulvermatall GmbH, Essen, Germany), Umformtechnik, Vol 26, No 5, 1992, 340-341. (In German). T h e p r o d u c t i o n of PM p a r t s f r o m s p h e r i c a l g a s a t o m i z e d p o w d e r s is discussed with regard to freedom from segregation and non-metallic inclusions a n d fabrication to high density by HIP. High t a p densities a n d good flow properties are r e p o r t e d to e n a b l e p r o d u c t i o n of nonp o r o u s a n d w e a r r e s i s t a n t p a r t s w h i c h are suitable for surface t r e a t m e n t processing. Co base alloys a n d s t r u c t u r a l a n d h o t work tool steels are considered. P R O C E S S DEVELOPMENTS FOR HIGH S T R E N G T H AND HIGH DUCTILITY S I N T E R E D PARTS
T. K o h n o ( M i t s u b u s h i M a t e r i a l s Corp, Omiya, J a p a n ) , J. Japan Soc. Powder and Powder Metallurg3,, Vol 40, No 6, 1993, 579-584. (In Japanese). It is recognised t h a t PM p r o c e s s i n g offers a lower cost route to t h e p r o d u c t i o n of m e t a l p a r t s b u t t h a t higher costs may be i n c u r r e d for t h e m a n u f a c t u r e of h i g h p e r f o r m a n c e materials. Trials of m a t e r i a l s with high strength and ductility are described. The alloys t e s t e d were h i g h s t r e n g t h Fe-Cu-C-P, w h i c h h a d s m a l l d i m e n s i o n a l change during sintering. WNi-Fe heavy alloys with high s t r e n g t h a n d ductility, s i n t e r forged high speed steel m a d e from w a t e r atomized p o w d e r a n d two stage p o w d e r forging of a rapidly solidified A1 alloy powder.
MPR September 1994 53
Coatings DETONATION COATING P R O C E S S E S
V. Kadyrov et al (Academy of Sciences, Kiev, Ukraine), Trans. PM Assoc. of India, Vol 20, 1993, 1-5. The d e t o n a t i o n process is described in which m e t a l powder is d e p o s i t e d on a s u b s t r a t e with explosive force. Equipment, physico-chemical reactions, m e t a l l o g r a p h y of t h e c o a t i n g s a n d a p p l i c a t i o n s a r e discussed.
Electrical and magnetic materials E F F E C T S OF HEAT TREATMENT ON MICROSTRUCTURE AND COERCIVITY OF IRON-NEODYMIUM-BORON
LITERATURE
REVIEW
It is r e p o r t e d t h a t sintering of WiB2with Fe results in t h e f o r m a t i o n of Fe2B t h u s a b s o r b i n g some of t h e ductile b i n d e r phase, Ti203 also forming t h i s being a t t r i b u t e d to impurities. The use of a m e t a l b i n d e r w i t h a g r e a t e r a f f i n i t y f o r B t h a n Fe w a s i n v e s t i g a t e d a n d single p h a s e Fe-Cr-Ni a n d two p h a s e Fe2B-Fe-Ni-Cr b i n d e r s were studied with b i n d e r c o n t e n t s in t h e r a n g e 5 to 20vo1%. It is r e p o r t e d t h a t b e t t e r hardness/fracture toughness combinations were o b t a i n e d t h a n with WC-Co or Ti (C,N) cermets. The use of fine grained TiBzB, w i t h low O a n d C contents, shows p o t e n t i a l for f u r t h e r d e v e l o p m e n t as t h e s e will give i m p r o v e d sintering, m i c r o s t r u c t u r e s a n d properties. HEALING OF CRACKS IN T U N G S T E N CARBIDE-COBALT IN THE T E M P E R A T U R E RANGE 600°C TO 800°C
J.P. Yang et al (Korea Advanced Inst. of Science a n d Technology, Korea), Materials Science and Engineering B, Vol B18, No 1, 1993, 78-82. A r e p o r t of investigations into t h e effects of cyclic h e a t i n g a n d cooling o n t h e m i c r o s t r u c t u r e a n d magnetic p r o p e r t i e s of sintered Fe-Nd-B m a g n e t s is presented. The v a r i a t i o n in coercivity is s h o w n to be reversible d e p e n d i n g on cooling rate. Assintered or cooled at 4.5°C/min t h e r e was low coercivity b u t on r a p i d cooling at 200°C/min the coercivity was high. This is a t t r i b u t e d to t h e presence of a h e x a g o n a l Nd rich p h a s e in t h e fast cooled alloys.
W. B a r l o w - J o n e s e t al ( U n i v e r s i t y of Witwatersrand, J o h a n n e s b u r g h , S o u t h Africa), Int. J. Refractory Metals & Hard Materials, Vol 12, No 2, 1993-1994, 89-93. It is r e p o r t e d t h a t cracks in WC-Co partially heal when annealed. An investigation of WC-6%Co a n d WC-10%Co, h e a t t r e a t e d a t 600, 700 or 800°C, is described. A m o d e l is p r o p o s e d w h i c h agrees well with t h e e x p e r i m e n t a l results. Healing is a t t r i b u t e d to re-sintering in t h e b i n d e r p h a s e only w h e n t h e crack interface s e p a r a t i o n is small e n o u g h for asperities in t h e surface to bridge t h e crack, mainly n e a r to t h e crack tips.
Hard materials and tool steels
TURNING T E S T S WITH TITANIUM DIBORIDE C E R M E T S
PROPERTIES OF HIP AND S I N T E R E D HIGH S P E E D S T E E L
K Veda et al (Mitsubushi Materials Corporation, Omiya, J a p a n ) , J. Japan Soc. Powder and Powder MeLallurgy, Vol 40, No 6, 1993, 589-592. (In Japanese). A c o m p a r i s o n is m a d e between HSS p r o c e s s e d by HIP or by c o n v e n t i o n a l sintering. The HIP steel is r e p o r t e d to have s u p e r i o r p r o p e r t i e s a f t e r v a c u u m sintering. It is n o t e d t h a t HIP p a r t s can be m a d e to closer d i m e n s i o n a l t o l e r a n c e s (60 I~m) c o m p a r e d with 150 I~m for t h e conventionally sintered steel. The HIP steel h a s the higher s t r e n g t h at 365 Kgf/mm 2 c o m p a r e d with 270 Kgf/mm '~. NEW HARD METALS BASED ON TITANIUM DIBORIDE
L.S. Sigl et al (Electroschmelzwerk Kempten, Kempton, Germany), Int. J. Refractory Metals & Hard Materials, Vol 12, No 2, 1993-1994, 71-88.
L.S. Sigl et al (Electroschmelzwerk Kempten, Kempten, Germany), Int. J. Refractory Metals & Hard Materials, Vol 12, No 2, 1993-1994, 95-99. The cutting performance of TiB2 cermets, against a C steel, a cast iron a n d a hypoeutectic A1-Si alloy were c o m p a r e d with Ti(C,N)-Ni a n d A1203-ZrO 2. The WiB2 materials are r e p o r t e d to show s u p e r i o r performance in spite of a coarse m i c r o s t r u c t u r e a n d p o o r high t e m p e r a t u r e s t r e n g t h in t h e b i n d e r p h a s e w h e n used to cut cast iron a n d A1-Si. It is considered t h a t f u r t h e r i m p r o v e m e n t s are r e q u i r e d a n d work to a t t a i n this is said to be in progress. MICROSTRUCTURE A N D CUTTING PERFORMANCE OF TITANIUM CARBIDE C E R M E T S CONTAINING NITROGEN
M. Ueki (Toshiba Tungaloy Co, Kawasaki, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 7, 1993, 743-750. (In Japanese).
A n i n v e s t i g a t i o n o f t h e e f f e c t s of a d d i t i o n s of TaC, NbC or WC o n t h e m i c r o s t r u c t u r e s a n d cutting p e r f o r m a n c e of TiC-20vol%TiN-7%Mo2C-8%Ni and c h a n g e s c a u s e d by h e a t t r e a t m e n t is described.
Intermetallic materials HIP P R O C E S S I N G OF TITANIUM ALUMINIDE FROM B L E N D E D ELEMENTAL POWDERS
P. Lee-Sullivan, J. Materials Processing Technology, Vol 38, No I-2, 1993, 483-489. The p r o d u c t i o n of ~ from b l e n d e d equiatomic m i x t u r e s of e l e m e n t a l powders by HIP or by CIP followed by contalnerless HIP, is described. The HIP alloy is shown to consist of e q u i a x e d TiA1. In t h e CIP/CHIP m a t e r i a l t h e r e was diffusion of A1 in Ti a n d t h e incomplete dissolution gave a m i x t u r e of 3fILM, a2TiaA1 with m u c h porosity.
PM components FIELD USE OF WEAR R E S I S T A N T PM MATERIALS
J. Potschke (Krupp Pulvermatall GmbH, Essen, Germany), Umformtechnik, Vol 26, No 5, 1992, 340-341. (In German). T h e p r o d u c t i o n of PM p a r t s f r o m s p h e r i c a l g a s a t o m i z e d p o w d e r s is discussed with regard to freedom from segregation and non-metallic inclusions a n d fabrication to high density by HIP. High t a p densities a n d good flow properties are r e p o r t e d to e n a b l e p r o d u c t i o n of nonp o r o u s a n d w e a r r e s i s t a n t p a r t s w h i c h are suitable for surface t r e a t m e n t processing. Co base alloys a n d s t r u c t u r a l a n d h o t work tool steels are considered. P R O C E S S DEVELOPMENTS FOR HIGH S T R E N G T H AND HIGH DUCTILITY S I N T E R E D PARTS
T. K o h n o ( M i t s u b u s h i M a t e r i a l s Corp, Omiya, J a p a n ) , J. Japan Soc. Powder and Powder Metallurg3,, Vol 40, No 6, 1993, 579-584. (In Japanese). It is recognised t h a t PM p r o c e s s i n g offers a lower cost route to t h e p r o d u c t i o n of m e t a l p a r t s b u t t h a t higher costs may be i n c u r r e d for t h e m a n u f a c t u r e of h i g h p e r f o r m a n c e materials. Trials of m a t e r i a l s with high strength and ductility are described. The alloys t e s t e d were h i g h s t r e n g t h Fe-Cu-C-P, w h i c h h a d s m a l l d i m e n s i o n a l change during sintering. WNi-Fe heavy alloys with high s t r e n g t h a n d ductility, s i n t e r forged high speed steel m a d e from w a t e r atomized p o w d e r a n d two stage p o w d e r forging of a rapidly solidified A1 alloy powder.
MPR September 1994 53